Halacha

הלכה א
הַקוֹשֵׁר קֶשֶׁר שֶׁל קַיָּמָא וְהוּא מַעֲשֵׂה אֻמָּן חַיָּב. כְּגוֹן קֶשֶׁר הַגַּמָּלִין וְקֶשֶׁר הַסַּפָּנִין וְקִשְׁרֵי רְצוּעוֹת מִנְעָל וְסַנְדָּל שֶׁקּוֹשְׁרִין הָרַצְעָנִין בִּשְׁעַת עֲשִׂיָּתָן. וְכֵן כָּל כַּיּוֹצֵא בָּזֶה. אֲבָל הַקּוֹשֵׁר קֶשֶׁר שֶׁל קַיָּמָא וְאֵינוֹ מַעֲשֵׂה אֻמָּן פָּטוּר. וְקֶשֶׁר שֶׁאֵינוֹ שֶׁל קַיָּמָא וְאֵינוֹ מַעֲשֵׂה אֻמָּן מֻתָּר לְקָשְׁרוֹ לְכַתְּחִלָּה:
כסף משנה
1.
A person who ties a knot which is intended to remain permanently and which can be tied [only] by craftsmen1A knot that requires professional expertise and cannot be tied by an untrained person. is liable. Included in this category are the knots tied by camel drivers, the knots tied by seamen, the knots tied by shoemakers when making shoes and sandals.2The fishermen who would catch chilazon that were necessary for the construction of the Sanctuary would tie their nets with special knots that required professional expertise. Similarly, these knots were intended to remain permanently. Therefore, tying such a knot is considered a category of forbidden labor.
It must be emphasized that Rashi and Rabbenu Asher do not accept the criteria mentioned here by the Rambam (which are based on the Halachot of Rabbenu Yitzchak Alfasi from Shabbat 111b). They maintain that tying a knot with the intention that it remain permanently causes one to be liable if the knot is strong enough to remain, even though tying the knot does not require professional expertise.
The Shulchan Aruch (Orach Chayim 317:1) follows the Rambam's perspective. The Ramah, however, rules according to the view of Rashi and Rabbenu Asher.

One who ties a knot that is intended to remain permanently, but does not require a craftsmen [to tie it], is not liable. A knot that will not remain permanently and does not require a craftsman may be tied with no compunctions.

הלכה ב
כֵּיצַד. נִפְסְקָה לוֹ רְצוּעָה וּקְשָׁרָהּ, נִפְסַק הַחֶבֶל וּקְשָׁרוֹ, אוֹ שֶׁקָּשַׁר חֶבֶל בִּדְלִי אוֹ שֶׁקָּשַׁר רֶסֶן בְּהֵמָה הֲרֵי זֶה פָּטוּר. וְכֵן כָּל כַּיּוֹצֵא בְּאֵלּוּ הַקְּשָׁרִים שֶׁהֵן מַעֲשֵׂה הֶדְיוֹט וְכָל אָדָם קוֹשֵׁר אוֹתָן לְקַיָּמָא. וְכָל קֶשֶׁר שֶׁאֵינוֹ שֶׁל קַיָּמָא אִם קְשָׁרוֹ קֶשֶׁר אֻמָּן הֲרֵי זֶה אָסוּר:
כסף משנה
2.
How is [the intermediate category] defined? If one of a person's sandal straps tore and he tied it, a rope tore and one tied it, one tied a rope to a bucket, or one tied the bridle of an animal, the person is not liable. The same applies to all other knots that do not require professional expertise, but are always tied with the intention that they remain permanently.3According to Rashi and Rabbenu Asher, one would be liable for tying such knots.
Any knot that is not intended to remain permanently is forbidden to be tied using a knot that requires professional expertise.4Rabbi Yosef Korcus explains the difference between the two clauses of this halachah. Since the knots mentioned in the first clause are intended to last permanently, one would think that one is liable. Therefore, the Rambam emphasizes that one is not.
By contrast, since the knots mentioned in the second clause are not intended to last permanently, one would think that it is permitted to tie them. Hence, the Rambam emphasizes that this is forbidden.

הלכה ג
קוֹשֶׁרֶת אִשָּׁה מִפְתְּחֵי הֶחָלוּק אַף עַל פִּי שֶׁיֵּשׁ לוֹ שְׁנֵי פְּתָחִים, וְחוּטֵי סְבָכָה אַף עַל פִּי שֶׁהוּא רָפוּי בְּרֹאשָׁהּ, וּרְצוּעוֹת מִנְעָל וְסַנְדָּל שֶׁקּוֹשְׁרִין אוֹתָן עַל הָרֶגֶל בִּשְׁעַת מַלְבּוּשׁ, וְנוֹדוֹת יַיִן וְשֶׁמֶן אַף עַל פִּי שֶׁיֵּשׁ לוֹ שְׁתֵּי אָזְנַיִם, וּקְדֵרָה שֶׁל בָּשָׂר אַף עַל פִּי שֶׁיְּכוֹלָה לְהוֹצִיא הַבָּשָׂר וְלֹא תַּתִּיר הַקֶּשֶׁר. וְקוֹשְׁרִין דְּלִי בִּמְשִׁיחָה אוֹ בְּאַבְנֵט וְכַיּוֹצֵא בּוֹ אֲבָל לֹא בְּחֶבֶל. וְקוֹשְׁרִין לִפְנֵי הַבְּהֵמָה אוֹ בְּרַגְלָהּ בִּשְׁבִיל שֶׁלֹּא תֵּצֵא אַף עַל פִּי שֶׁיֵּשׁ לָהּ שְׁנֵי אִסָּרוֹת. וְחֶבֶל שֶׁהָיָה קָשׁוּר בַּפָּרָה קוֹשְׁרוֹ בָּאֵבוּס. הָיָה קָשׁוּר בָּאֵבוּס קוֹשְׁרוֹ בַּפָּרָה. אֲבָל לֹא יָבִיא חֶבֶל מִתּוֹךְ בֵּיתוֹ וְיִקְשֹׁר בַּפָּרָה וּבָאֵבוּס. וְאִם הָיָה חֶבֶל גַּרְדִּי שֶׁמֻּתָּר לְטַלְטְלוֹ הֲרֵי זֶה מֵבִיא וְקוֹשֵׁר בַּפָּרָה וּבָאֵבוּס. מִפְּנֵי שֶׁכָּל אֵלּוּ הַקְּשָׁרִים מַעֲשֵׂה הֶדְיוֹט הֵן וְאֵינָן שֶׁל קַיָּמָא אֶלָּא פַּעַם קוֹשֵׁר וּפַעַם מַתִּיר וּלְפִיכָךְ מֻתָּר לִקְשֹׁר אוֹתָן לְכַתְּחִלָּה. חוֹתָלוֹת שֶׁל תְּמָרִים וְשֶׁל גְּרוֹגָרוֹת מַתִּיר וּמַפְקִיעַ וְחוֹתֵךְ וְנוֹטֵל וְאוֹכֵל:
כסף משנה
3.
A woman may tie the opening of her cloak although it has two openings.5This law - and most of the subsequent clauses of this halachah - are based on Shabbat 15:2. In each of the clauses, the Rambam (based on the Talmud) further develops the concepts stated in the Mishnah.
In this instance, Shabbat 112a explains that such a cloak had two straps, each one extending from one corner of the garment to the other. Since a woman could remove the garment by untying only one strap and slipping it over her head, there is reason to think that one of the knots would be considered as permanent, and therefore forbidden to be tied on the Sabbath. Nevertheless, this hypothesis is not accepted, and tying and untying both knots is permitted.
She may tie the strands of a hairnet although it hangs loosely on her head.6Shabbat (loc. cit.) relates that these nets are also tied to a woman's hair. Hence, since the net is not tight fitting, it could be slipped off without untying it. Thus one might consider the knot as permanent. Nevertheless, since usually, these nets are untied, there is no difficulty in tying them.
One may tie the straps of shoes and sandals that are tied around one's foot when donning them.7Since they will be untied when the shoes are removed, tying them is permitted. One may tie pouches of wine and pouches of oil although they have two protrusions.8Shabbat (loc. cit.) explains that the pouches were tied at each of these protrusions. Although the liquid could be removed by opening only one of them, neither of the knots is considered to be permanent, because it was customary to open both knots, for then the liquids flowed more freely. One may tie a pot of meat although it is possible to remove the meat without untying the knot.9Shabbat (loc. cit.) states that although the food could be removed from the pot without untying the knot, we do not consider the knot permanent. We assume that the people will follow the usual practice and untie the knots before opening the pot.
One may tie a bucket with a linen cord, a belt or another similar entity, but not with an ordinary rope.10It is forbidden to tie a bucket with an ordinary rope, because it is likely that one will leave the rope there permanently. A linen cord, a belt, or another similar entity is not really fit for this purpose. Hence, it is probable that one will untie it after using it (Maggid Mishneh, based on Shabbat 113a).
Even though the Rambam would maintain that tying an ordinary rope to a bucket does not make one liable according to Torah law, there is still reason for this additional decree.
One may tie a rope before an animal or tie it to an animal's foot so that it will not go out, although this involves two knots.11The animal's owner closed the stall by tying a rope before it, tying it to both ends of the entrance (or, according to other commentaries, by tying two ropes). Although the stall could be opened by untying only one knot, we do not assume that the rope(s) will be left there permanently (Shabbat 112b).
If a rope is tied to a cow, one may tie it to its feeding trough. If a rope is tied to a feeding trough, one may tie it to a cow. One may not, however, bring a rope from one's home and tie it to [both] a cow and a feeding trough. If, however, one has a weaver's rope which one is permitted to carry,12This phrase is the key to the Rambam's understanding of this law (which is based on Shabbat 113a). Since tying the animal does not necessitate using a knot that requires professional expertise, the Rambam would not consider it prohibited according to Torah law. And as the Rambam states, since the intention is not to leave the animal tied permanently, there is no reason for even a Rabbinic prohibition. Nevertheless, since it is forbidden to use a rope on the Sabbath unless it was designated for use beforehand, one may not bring a rope from home. If one tied the rope to the animal or to the feeding trough before the commencement of the Sabbath, however, it is obvious that one intended to use it on the Sabbath. one may bring it and tie it to both the cow and the feeding trough.
[The rationale for these laws is that] all [the above] knots do not require professional expertise, nor are they intended to remain. On the contrary, a person ties them and unties them at will. Therefore, it is permitted to tie them with no compunctions.
One may untie the openings of baskets of dates and dried figs, break off or cut off the cord, take them and eat them.13Shabbat 146a explains that dates and dried figs were strung on a cord and placed in palm branch baskets. One may untie the baskets and cut the cords and eat the fruit.

הלכה ד
כָּל שֶׁרָאוּי לְמַאֲכַל בְּהֵמָה מֻתָּר לִקְשֹׁר אוֹתוֹ בְּשַׁבָּת. לְפִיכָךְ אִם נִפְסְקָה רְצוּעַת סַנְדָּלוֹ בְּכַרְמְלִית נוֹטֵל גֶּמִי לַח הָרָאוּי לְמַאֲכַל בְּהֵמָה וְכוֹרֵךְ עָלָיו וְקוֹשֵׁר הַגֶּמִי. נִשְׁמְטָה לוֹ רְצוּעַת מִנְעָל וְסַנְדָּל אוֹ שֶׁנִּשְׁמַט רֹב הָרֶגֶל מֻתָּר לְהַחֲזִיר הָרְצוּעוֹת לִמְקוֹמָן וּבִלְבַד שֶׁלֹּא יִקְשֹׁר:
כסף משנה
4.
Any substance that is fit to be used as animal fodder may be used for tying on the Sabbath.14Other substances fit for tying would be muktzeh, forbidden to be carried on the Sabbath. Therefore, if the straps of a person's sandals snapped in a carmelit, he may take a moist reed15In his Commentary on the Mishnah (Shabbat 24:5), the Rambam explains that a reed will never be used to tie a permanent knot. that is fit to be eaten by an animal, wind it around [the sandal] and tie it.16This halachah is based on Shabbat 112a, which relates that Rav Yirmiyah saw Rabbi Abahu act in this manner when his sandal strap snapped on the Sabbath. That narrative took place in a carmelit.
The Talmud continues mentioning a situation where Abbaye's sandal strap snapped in a private courtyard and Rav Yosef forbade him to employ a similar technique. The Shulchan Aruch (Orach Chayim 308:15) mentions both these rulings.

If a sandal strap slips from its place, or one's foot slips from the sandal, one may return the strap to its place,17In his gloss on the Shulchan Aruch (Orach Chayim 317:2), the Ramah mentions that this is permitted only when it does not involve much effort. provided one does not tie a knot.18The Magen Avraham 317:8 states that were one to tie a knot, it would be forbidden, because we can assume that the knot would be left permanently.

הלכה ה
הָעֲנִיבָה מֻתֶּרֶת לְפִי שֶׁאֵינָהּ מִתְחַלֶּפֶת בִּקְשִׁירָה. לְפִיכָךְ הַחֶבֶל שֶׁנִּפְסַק מְקַבֵּץ שְׁנֵי קְצוֹתָיו וְכוֹרֵךְ עָלָיו מְשִׁיחָה וְעוֹנֵב עֲנִיבָה:
כסף משנה
5.
It is permitted to tie a loop [on the Sabbath],19The Ramah (Orach Chayim 317:5) states that one may even tie a single knot with a loop above it, provided one does not intend to leave it permanently. See Shulchan Aruch HaRav 317:3, Mishnah Berurah 317:29. for it will not be interchanged with a knot.20I.e., there is no reason to decree that a loop is forbidden, lest one tie a knot. Therefore, if a rope snapped, one may gather the two ends together, wind a linen cord around them and tie a loop.21The Kessef Mishneh objects to the Rambam's decision, noting that Shabbat 113a states that if one employs a linen cord, one may tie a knot, but if one employs a rope, one must tie a loop. In his Shulchan Aruch (Orach Chayim 317:4), Rav Yosef Karo rules according to his understanding of that passage.
Yad David and others reconcile the Rambam's wording, explaining that he means "wind a linen cord around it, or tie it [i.e., the rope itself] with a loop."

הלכה ו
מֻתָּר לִקְשֹׁר קֶשֶׁר שֶׁאֵינוֹ שֶׁל קַיָּמָא לִדְבַר מִצְוָה. כְּגוֹן שֶׁיִּקְשֹׁר לִמְדֹּד שִׁעוּר מִשִּׁעוּרֵי הַתּוֹרָה. נִימַת כִּנּוֹר שֶׁנִּפְסַק קוֹשְׁרִין אוֹתָהּ בַּמִּקְדָּשׁ אֲבָל לֹא בַּמְּדִינָה. וְלֹא יִקְשֹׁר נִימָא לְכַתְּחִלָּה אֲפִלּוּ בַּמִּקְדָּשׁ:
כסף משנה
6.
It is permissible to tie a knot that is not permanent in nature for the purpose of a mitzvah.22In his Commentary on the Mishnah (Shabbat 24:5), the Rambam states that leniency was granted with regard to tying knots that are intended to remain permanently if they are tied for the sake of a mitzvah on the Sabbath. Rashi, by contrast maintains that the Mishnah grants leniency with regard to measuring alone and not with regard to tying knots that are not temporary in nature.
On this basis, this halachah must be interpreted to mean that one is allowed to tie knots that will not remain permanently, even with a knot that requires professional expertise, or a knot that is intended to remain for an extended period if it does not require professional expertise. (See the Be'ur Halachah 317.)
For example, one may tie a knot to calibrate one of the Torah's measures.23The concluding Mishnah in the tractate of Shabbat states that "In the days of Rabbi Tzadok's father and Abba Shaul ben Botnit, they... tied a cup with a reed to ascertain whether a vat possessed an opening that was a handbreadth in size."
One may tie a harp string that snaps in the Temple,24This is not considered a permanent knot, because we assume that after the Sabbath it will be changed. There are opinions in the Talmud (Eruvin 102b) that permit only a loop to be tied. Based on the p rinciple, "Restrictions in the category of sh'vut are not enforced in the Temple," the Rambam, however, chooses the more lenient view (Kessef Mishneh, Or Sameach). but not anywhere else. One may not tie a harp string for the first time on the Sabbath, even in the Temple.

הלכה ז
כָּל קֶשֶׁר שֶׁחַיָּבִין עַל קִשּׁוּרוֹ כָּךְ חַיָּבִין עַל הֶתֵּרוֹ. וְכָל קֶשֶׁר שֶׁהַקּוֹשֵׁר אוֹתוֹ פָּטוּר כָּךְ הַמַּתִּיר אוֹתוֹ פָּטוּר. וְכָל קֶשֶׁר שֶׁמֻּתָּר לְקָשְׁרוֹ כָּךְ מֻתָּר לְהַתִּירוֹ:
כסף משנה
7.
A person is liable for untying any knot that he is liable for tying.25Just as tying is one of the 39 categories of forbidden labor, so is untying. Accordingly, all the principles described above concerning tying apply with regard to untying. Whenever a person is not liable for tying a knot, he is not liable for untying it. Whenever a person is permitted to tie a knot, he is permitted to untie it.26Tosafot (Shabbat 73a) states that one is liable only when one unties with the intent of retying, for this was the practice of the chilazon fishermen in the construction of the Sanctuary. Significantly, the Rambam does not mention that requirement. Rashi (Shabbat 74b) rules more stringently, holding one liable even when one does not have the intent of retying the knot immediately. Needless to say, even according to Rashi's view, one must untie the knot for a positive purpose.

הלכה ח
הַפּוֹתֵל חֲבָלִים מִן הַהוּצִין וּמִן הָחֶלֶף אוֹ מִחוּטֵי צֶמֶר אוֹ מִחוּטֵי פִּשְׁתָּן אוֹ חוּטֵי שֵׂעָר וְכַיּוֹצֵא בָּהֶן הֲרֵי זֶה תּוֹלֶדֶת קוֹשֵׁר וְחַיָּב. וְשִׁעוּרוֹ כְּדֵי שֶׁיַּעֲמֹד הַחֶבֶל בִּפְתִילָתוֹ בְּלֹא קְשִׁירָה שֶׁנִּמְצֵאת מְלַאכְתּוֹ מִתְקַיֶּמֶת. וְכֵן הַמַּפְרִיד אֶת הַפְּתִיל הֲרֵי זֶה תּוֹלֶדֶת מַתִּיר וְחַיָּב. וְהוּא שֶׁלֹּא יִתְכַּוֵּן לְקַלְקֵל בִּלְבַד. וְשִׁעוּרוֹ כְּשִׁעוּר הַפּוֹתֵל:
כסף משנה
8.
A person who winds together a rope from palm branches, love grass,27Our translation is based on Rav Kapach's version of the Rambam's Commentary on the Mishnah (Keilim 17:17). strands of wool, strands of flax, strands of goat's hair or the like is liable for performing a derivative of the [forbidden] labor of tying.28The commentaries question why this activity is not considered a derivative of the forbidden labor of spinning thread. The Migdal Oz resolves this question by citing as a source the Jerusalem Talmud, Shabbat 15:1. That passage relates that an experienced tailor connects two ends of a thread together by undoing their twine, and then rewinding them. Since the tailor's object is to connect the two ends, the activity is considered a derivative of tying.
The minimum measure for which one is liable is a length of rope sufficient to remain wound without being tied, for then the work the person performed is permanent.29See Chapter 9, Halachah 13 and Halachah 1 of this chapter.
Similarly, a person who unwinds cords performs a derivative of the forbidden labor of untying and is liable. [This applies] provided one's intent is not merely destructive in nature.30See Chapter 1, Halachot 17-18. The minimum measure for which one is liable is the same as that for winding a cord.

הלכה ט
הַתּוֹפֵר שְׁתֵּי תְּפִירוֹת חַיָּב. וְהוּא שֶׁקָּשַׁר רָאשֵׁי הַחוּט מִכָּאן וּמִכָּאן כְּדֵי שֶׁתַּעֲמֹד הַתְּפִירָה וְלֹא תִּשָּׁמֵט. אֲבָל אִם תָּפַר יֶתֶר עַל שְׁתֵּי תְּפִירוֹת אַף עַל פִּי שֶׁלֹּא קָשַׁר חַיָּב שֶׁהֲרֵי מִתְקַיֶּמֶת הַתְּפִירָה. וְהַמּוֹתֵחַ חוּט שֶׁל תְּפִירָה בְּשַׁבָּת חַיָּב מִפְּנֵי שֶׁהוּא מִצָּרְכֵי הַתְּפִירָה:
כסף משנה
9.
A person who sews two stitches is liable,31This is one of the 39 categories of forbidden labor. provided he ties32Many of the commentaries question why the Rambam does not mention that the person is also liable for tying. It would appear, however, that this knot does not require professional expertise. Furthermore, sewing and not tying, is the subject of the Rambam's statements here. the stitches at both ends so that they will remain and not slip out.33Only if the stitches are tied at both ends will they remain permanently. Rav Kapach notes that in Hilchot Kilayim 10:24, the Rambam does not require the two stitches to be attached for one to be liable for sha'atnez, echoing a similar ruling of the Mishnah (Kilayim 9:10).
Rav Kapach explains that the obligations of the two prohibitions differ. With regard to sha'atnez, there is no requirement that wool and linen be permanently attached for one to be liable. In contrast, if the forbidden activity one performs on the Sabbath is not lasting in nature, one is not liable.
If, however, one sews an additional stitch, one is liable even if one did not tie [the ends], for one's stitching will remain.
A person who pulls taut a thread used for sewing34After one sews several stitches, one pulls the thread taut (Shabbat 75a). on the Sabbath is liable, because this activity is necessary for sewing.

הלכה י
הַקּוֹרֵעַ כְּדֵי לִתְפֹּר שְׁתֵּי תְּפִירוֹת עַל מְנָת לִתְפֹּר שְׁתֵּי תְּפִירוֹת חַיָּב. אֲבָל הַקּוֹרֵעַ לְהַפְסִידָהּ פָּטוּר מִפְּנֵי שֶׁהוּא מְקַלְקֵל. הַקּוֹרֵעַ בַּחֲמָתוֹ אוֹ עַל מֵת שֶׁהוּא חַיָּב לִקְרֹעַ עָלָיו חַיָּב מִפְּנֵי שֶׁמְּיַשֵּׁב אֶת דַּעְתּוֹ בְּדָבָר זֶה וְיָנוּחַ יִצְרוֹ וְהוֹאִיל וַחֲמָתוֹ שׁוֹכֶכֶת בְּדָבָר זֶה הֲרֵי הוּא כִּמְתַקֵּן וְחַיָּב. וְהַפּוֹתֵחַ בֵּית הַצַּוָּאר בְּשַׁבָּת חַיָּב:
כסף משנה
10.
A person who tears [a length of a garment] sufficient to tie two stitches35Our translation is based on the gloss of Rabbi Akiva Eiger. for the sake of tying two stitches is liable.36This is one of the 39 categories of forbidden labor. Although this activity was performed in the Sanctuary for this purpose, the Rambam maintains that a person who performs a מלאכה שאינה צריכה לגופה is liable. Therefore, he maintains that one is liable even if he tears for other purposes. The Mishnah (Shabbat 7:2), however, describes this forbidden labor as "one who tears to sew two stitches." In contrast, one who tears with the intent to ruin is not liable, for [his activity] is destructive in nature.37See Chapter 1, Halachot 17-18.
A person who tears in a fit of rage or [one who rends his garments] for the sake of a deceased person for whom he is required to rend his garments38The Rambam discusses the obligation to rend one's garments over a deceased person in Hilchot Eivel, Chapters 8 and 9. is liable, for by doing so he settles his mind and calms his natural inclination. Since his anger is soothed through this act, it is considered to be constructive in nature and he is liable.39See Chapter 8, Halachah 8, and notes.
A person who makes an opening for a neck [in a garment] on the Sabbath is liable.40The Merkevet HaMishnah states that this refers to simply opening up a place for the head in a garment. Since the Rambam maintains that a person who performs a מלאכה שאינה צריכה לגופה is liable, he maintains that a person is liable for cutting such an opening even if he does not sew it.
Rashi (Shabbat 48a) states that one is liable for this activity for performing a derivative of the forbidden category of labor מכה בפטיש, making an entity ready for use. (Rashi cannot hold one liable for tearing, since he differs with the Rambam and maintains that a person who performs a מלאכה שאינה צריכה לגופה is not liable.)
The latter interpretation is reflected in the statements of Rabbenu Avraham, the Rambam's son, quoted in the Ma'aseh Rokeach, which explain that after a garment was completed, the neck was sewed up with temporary stitches to show that it was never worn. When the purchaser desired to put on the garment, these stitches were undone. See also Shulchan Aruch and Ramah (Orach Chayim 317:3).

הלכה יא
הַמְדַבֵּק נְיָרוֹת אוֹ עוֹרוֹת בְּקוֹלָן שֶׁל סוֹפְרִים וְכַיּוֹצֵא בּוֹ הֲרֵי זֶה תּוֹלֶדֶת תּוֹפֵר וְחַיָּב. וְכֵן הַמְפָרֵק נְיָרוֹת דְּבוּקִין אוֹ עוֹרוֹת דְּבוּקִין וְלֹא נִתְכַּוֵּן לְקַלְקֵל בִּלְבַד הֲרֵי זֶה תּוֹלֶדֶת קוֹרֵעַ וְחַיָּב:
כסף משנה
11.
A person who attaches paper or hides together with scribe's glue and the like is liable for performing a derivative of the forbidden labor of sewing.41For just as a person who sews, he attaches two entities to each other.
Conversely, a person who separates papers or hides that are stuck together is liable for performing a derivative of the forbidden labor of tearing42See the Magen Avraham 340:18, which states that the entities one separates must have been attached to each other with the intent of remaining permanently. Based on a similar rationale, the Chacham Tzvi (Responsum 39) does not hold one liable for opening an envelope, since the flap is not intended to remain permanently closed.
There is a common application of this principle today: the use of disposable baby diapers. Since the flap is not intended to remain permanently closed, fastening it or unfastening it is not considered as related to the forbidden labors of sewing and tearing.
if his intent is not merely destructive.

הלכה יב
הַבּוֹנֶה כָּל שֶׁהוּא חַיָּב. הַמַּשְׁוֶה פְּנֵי הַקַּרְקַע בְּבַיִת כְּגוֹן שֶׁהִשְׁפִּיל תֵּל אוֹ מִלֵּא גּוּמָא אוֹ גַּיְא הֲרֵי זֶה בּוֹנֶה וְחַיָּב. אֶחָד נָתַן אֶת הָאֶבֶן וְאֶחָד נָתַן אֶת הַטִּיט הַנּוֹתֵן הַטִּיט חַיָּב. וּבַנִּדְבָּךְ הָעֶלְיוֹן אֲפִלּוּ הֶעֱלָה אֶת הָאֶבֶן וְהִנִּיחָהּ עַל גַּבֵּי הַטִּיט חַיָּב. שֶׁהֲרֵי אֵין מַנִּיחִין עָלֶיהָ טִיט אַחֵר. וְהַבּוֹנֶה עַל גַּבֵּי כֵּלִים פָּטוּר:
כסף משנה
12.
A person is liable for building even the slightest amount.43This is one of the 39 categories of forbidden labor. One is liable for even the smallest act of construction, because if there was even the slightest nick or hole in one of the walls of the Sanctuary, hot lead would be poured into it to fill it (Shabbat 102b).
A person who levels the floor inside a house is liable.44For building, since with this activity, he prepares the building's floor. As mentioned in Chapter 8, Halachah 1, a person who performs this activity in a field is liable for plowing.
Significantly, based on Rashi (Eruvin 104a), Shulchan Aruch HaRav 313:24 also holds one liable for performing a derivative of building when one levels the ground in one's yard.
Whether he lowers a raised piece of earth or fills a cavity, he is considered to be building and is liable.
When one person places down a stone and another the mortar, the one who places down the mortar is liable.45Without the mortar, the stones would not hold in place. For the highest row [of stones], one is liable merely for lifting up the stone and placing it on the mortar, since other mortar is not placed upon it.
A person who builds on a base of utensils is not liable.46As the source for this halachah, the Maggid Mishneh points to the following passage from the Jerusalem Talmud (Shabbat 7:2, 12:1):

Where was [the forbidden labor of] building found in the Sanctuary? In the placement of the boards in their sockets.
Is this meant to imply that building on a base of utensils is considered building? The sockets are considered as the ground.

From this passage, it is clear that building on a base of utensils is not considered to be building according to Torah law. Note that this law refers to constructing a building by using a utensil as a base. The discussion of whether fashioning a utensil or connecting its parts is a derivative of the forbidden labor of building is discussed in the following halachah and notes.

הלכה יג
הָעוֹשֶׂה אֹהֶל קָבוּעַ הֲרֵי זֶה תּוֹלֶדֶת בּוֹנֶה וְחַיָּב. וְכֵן הָעוֹשֶׂה כְּלֵי אֲדָמָה כְּגוֹן תַּנּוּר וְחָבִית קֹדֶם שֶׁיִּשָּׂרְפוּ הֲרֵי זֶה תּוֹלֶדֶת בּוֹנֶה וְחַיָּב. וְכֵן הַמְגַבֵּן אֶת הַגְּבִינָה הֲרֵי זֶה תּוֹלֶדֶת בּוֹנֶה. וְאֵינוֹ חַיָּב עַד שֶׁיְּגַבֵּן כִּגְרוֹגֶרֶת. הַמַּכְנִיס יַד הַקַּרְדֹּם בְּתוֹךְ הָעֵץ שֶׁלּוֹ הֲרֵי זֶה תּוֹלֶדֶת בּוֹנֶה. וְכֵן כָּל כַּיּוֹצֵא בּוֹ. וְכֵן הַתּוֹקֵעַ עֵץ בְּעֵץ בֵּין שֶׁתָּקַע בְּמַסְמֵר בֵּין שֶׁתָּקַע בָּעֵץ עַצְמוֹ עַד שֶׁנִּתְאַחֵד הֲרֵי זֶה תּוֹלֶדֶת בּוֹנֶה וְחַיָּב:
כסף משנה
13.
A person who erects a permanent tent is liable for performing a derivative47The commentaries question why the erection of a tent is merely given the status of a derivative and is not considered to be a מעין מלאכה of the forbidden labor of building. The P'nei Yehoshua (Sukkah 16b) explains that a building is a stable structure, while a tent is far more fragile in nature.
The Even HaEzel explains that building involves two actions:
a) joining separate entities into a single whole;
b) spreading a roof over a structure.
Constructing a structure - or part of a structure - which contains both these actions is considered to be building proper. If either - but only one - of the two is involved, the act is deemed a derivative. Thus, erecting a tent is considered a derivative, because it involves spreading a roof, and making cheese is considered a derivative, because it involves joining separate entities into a single whole.
[of the forbidden labor] of building.48Significantly, neither in this halachah nor in Chapter 22, Halachah 27, when he mentions the Rabbinic prohibition against erecting a temporary tent does the Rambam explain whether the concept of permanence depends on the strength of the structure or the intent of the builder. It appears that he relies on his statements in Chapter 9, Halachah 13, "Whenever one performs a labor that does not have a permanent effect on the Sabbath, one is not liable." (See the notes on that halachah.)
Similarly, a person who fashions an earthenware utensil - e.g., an oven or a jug - before they are fired [in a kiln] is liable for performing a derivative [of the forbidden labor] of building.49Beitzah 22a relates a difference of opinion between the School of Hillel and the School of Shammai. The School of Shammai maintains that one is liable for performing a derivative of the forbidden labor of building when fashioning a utensil, while the School of Hillel rejects this thesis: "There is no [concept of] building with regard to utensils."
There is, however, a difference of opinion between the Rabbis about the interpretation of this statement. Rashi understands the statement simply. Fashioning a utensil can never be a derivative of building. One is liable for making a utensil, but one's liability stems from the forbidden labor of מכה בפטיש, completing a utensil. This view is shared by Rav Hai Gaon, Rabbenu Yitzchak Alfasi (according to Rabbenu Nissim), and others.
As obvious from this halachah, the Rambam differs and maintains that one is liable for building when fashioning a utensil. The leniency mentioned by the School of Hillel refers only to putting together a utensil that is made up of several component parts. [This is, however, forbidden by Rabbinic decree, because it resembles building (Chapter 22, Halachah 26).] Fashioning a new utensil, by contrast, is surely considered a derivative of building.
This latter opinion is shared by Tosafot (Shabbat 74b), the Ramban, the Rashba, and others. It is also accepted by the Shulchan Aruch (Orach Chayim 314:1).

Similarly, one who makes cheese performs a derivative [of the forbidden labor] of building.50See Chapter 7, Halachah 6. One is not liable until one makes an amount of cheese equivalent to the size of a dried fig.51Although one is liable for building even the slightest amount, with regard to this derivative the minimum measure for which one is liable is the size of a dried fig - the minimum measure associated with the labors related to food. Unless one makes an amount of cheese that size, one's activity is not significant at all.
A person who inserts the blade of an axe onto its handle or one who performs any similar activity performs a derivative [of the forbidden labor] of building. Similarly, one who attaches one piece of wood to another, whether he attaches them with a nail or by inserting one piece of wood into another until they become a single entity, is liable for performing a derivative [of the forbidden labor] of building.52The Rambam discusses the Rabbinic prohibitions associated with this activity in Chapter 22, Halachah 25. (See also the discussion of the issue in the Shulchan Aruch [Orach Chayim 313:9] and commentaries.)

הלכה יד
הָעוֹשֶׂה נֶקֶב כָּל שֶׁהוּא בְּלוּל שֶׁל תַּרְנְגוֹלִים כְּדֵי שֶׁיִּכָּנֵס לָהֶן הָאוֹרָה חַיָּב מִשּׁוּם בּוֹנֶה. הַמַּחֲזִיר דֶּלֶת שֶׁל בּוֹר וְשֶׁל דּוּת וְשֶׁל יָצִיעַ חַיָּב מִשּׁוּם בּוֹנֶה:
כסף משנה
14.
A person who makes even the slightest hole in a chicken coop to let light in is liable for building.53Note that in Halachah 16, the Rambam states that one who makes a hole in a building is liable for performing a derivative of the forbidden labor of מכה בפטיש. Similarly, in Chapter 23, Halachah 1, he states that a person who makes a hole in a chicken coop for the sake of letting light in and letting foul air out is liable for performing a derivative of the forbidden labor of מכה בפטיש.
Among the resolutions offered is that in addition to being liable for מכה בפטיש, one is liable for building (Lechem Mishneh). Alternatively, in this halachah, the Rambam mentions making a hole of any size, while in Chapter 23, he mentions making an opening, implying that it is of a larger size, and only then is one liable for מכה בפטיש (Sefer HaKovetz).

A person who returns a door of a well, a cistern, or a wing of a building [to its place] is liable for building.54These doors serve as part of the floor of the building. Therefore, putting them in place is a derivative of building. (See also Chapter 22, Halachah 25, and the commentary of the Maggid Mishneh.)

הלכה טו
הַסּוֹתֵר כָּל שֶׁהוּא חַיָּב. וְהוּא שֶׁיִּסְתֹּר עַל מְנָת לִבְנוֹת. אֲבָל אִם סָתַר דֶּרֶךְ הַשְׁחָתָה פָּטוּר. הַסּוֹתֵר אֹהֶל קָבוּעַ אוֹ שֶׁפֵּרֵק עֵץ תָּקוּעַ הֲרֵי זֶה תּוֹלֶדֶת סוֹתֵר וְחַיָּב וְהוּא שֶׁיִּתְכַּוֵּן לְתַקֵּן:
כסף משנה
15.
A person who demolishes even the slightest amount is liable, provided he demolishes with the intent to build.55Whenever the encampment of the Jewish people moved, the Sanctuary was taken down and then reconstructed in the new camp (Shabbat 31b).
The commentaries note that in Chapter 1, Halachah 18, the Rambam mentions that one is liable for "demolishing to build in its place," while in this halachah, the words "in its place" are not mentioned.
If his intent in demolishing is merely destructive, he is not liable.56As mentioned in Chapter 1, Halachah 17, one is not liable for performing any forbidden labor with merely a destructive intent. Nevertheless, as mentioned in Chapter 8, Halachah 8, if one destroys with the intent of venting one's anger, one is liable. Seemingly, the Rambam should have mentioned this point in this context as well.
A person who demolishes a permanent tent or separates a piece of wood attached to another is liable for performing a derivative [of the forbidden labor] of demolishing, provided his intent is to improve it [afterwards].57The Maggid Mishneh explains that the Rambam's intent is to illustrate how one is liable for demolishing for performing the converse of every positive activity for which one is liable for building.
Perhaps the Rambam's wording also alludes to the concept that a person is liable only when he demolishes a structure that is strong enough to last. If the structure he demolishes is not that sturdy, he is not liable. See Shulchan Aruch HaRav 313:19.

הלכה טז
הַמַּכֶּה בְּפַטִּישׁ הַכָּאָה אַחַת חַיָּב. וְכָל הָעוֹשֶׂה דָּבָר שֶׁהוּא גְּמַר מְלָאכָה הֲרֵי זֶה תּוֹלֶדֶת מַכֶּה בְּפַטִּישׁ וְחַיָּב. כֵּיצַד. הַמְנַפֵּחַ בִּכְלֵי זְכוּכִית וְהַצָּר בַּכְּלִי צוּרָה אֲפִלּוּ מִקְצָת הַצּוּרָה וְהַמְגָרֵד כָּל שֶׁהוּא וְהָעוֹשֶׂה נֶקֶב כָּל שֶׁהוּא בֵּין בְּעֵץ בֵּין בְּמַתֶּכֶת בֵּין בְּבִנְיָן בֵּין בְּכֵלִים הֲרֵי זֶה תּוֹלֶדֶת מַכֶּה בְּפַטִּישׁ וְחַיָּב. וְכָל פֶּתַח שֶׁאֵינוֹ עָשׂוּי לְהַכְנִיס וּלְהוֹצִיא אֵין חַיָּבִין עַל עֲשִׂיָּתוֹ:
כסף משנה
16.
A person who gives the [final] blow with a hammer is liable. [Similarly,] a person who performs any activity that represents the completion of a task is liable for performing a derivative of dealing [the final] hammer blow.58In his Commentary on the Mishnah (Shabbat 7:2), in definition of this category of forbidden labor, the Rambam writes:

A person who beats [an article] with a hammer, even at the conclusion of the work as the craftsmen do. They strike very light blows to straighten the surface of a utensil.... Therefore, every activity involved in fashioning and completing a utensil, planing it, polishing it, and making it attractive are all derivatives of dealing [the final] hammer blow.
This is what [our Sages implied with] their statement (Shabbat 75b), "For any activity that constitutes the completion of a task, one is liable for dealing [the final] hammer blow."

What is implied? A person who blows a glass vessel,59Tosafot, Shabbat 74b, asks: Since glass utensils are fashioned by blowing, why is one not liable for building as one is for making any other vessel? (See Halachah 13.) Indeed, the Jerusalem Talmud (Shabbat 7:2) holds a person who blows a glass utensil liable for performing that forbidden labor.
The Yesodei Yeshurun and Rav Kapach point out that Rashi (Shabbat 75b) explains that the activity referred to involves cutting a glass utensil by exposing it to a current of air. This is also implied by the Hebrew words המנפח בכלי זכוכית - "one who blows at a glass utensil."
one makes a design, or even a portion of a design, on a utensil,60If, however, one makes a drawing or a design on a paper (or on a similar substance), one is liable for performing a derivative of writing or dyeing (Jerusalem Talmud, Shabbat 7:2). (See also Chapter 11, Halachah 17, and Be'ur Halachah 340.) one who planes61The Maggid Mishneh in his gloss on Chapter 11, Halachah 7, renders the term used in our halachah as מגרר, "scrape." [the edges of a utensil],62See also Chapter 23, Halachah 4. one who makes a hole of even the smallest size in a piece of wood, a building, a piece of metal, or a utensil is liable for performing a derivative of dealing [the final] hammer blow.
One is not liable for making [a hole] unless it can be used to bring in and bring out.63I.e., to cause one to be held liable, any opening must be fit to be used as an entrance through which entities are brought in, and an exit through which entities are taken out.

הלכה יז
הַמֵּפִיס שְׁחִין בְּשַׁבָּת כְּדֵי לְהַרְחִיב פִּי הַמַּכָּה כְּדֶרֶךְ שֶׁהָרוֹפְאִין עוֹשִׂין שֶׁהֵן מִתְכַּוְּנִין בִּרְפוּאָה לְהַרְחִיב פִּי הַמַּכָּה הֲרֵי זֶה חַיָּב מִשּׁוּם מַכֶּה בְּפַטִּישׁ שֶׁזּוֹ הִיא מְלֶאכֶת הָרוֹפֵא. וְאִם הֵפִיסָה לְהוֹצִיא מִמֶּנָּה הַלֵּחָה שֶׁבָּהּ הֲרֵי זֶה מֻתָּר:
כסף משנה
17.
A person who pierces a blister on the Sabbath to widen the opening of the wound, as physicians do, with the intent of widening the opening of the wound is liable for performing [a derivative of] dealing [the final] hammer blow,64The Ra'avad, Rashi (Shabbat 107a), and others maintain that performing this activity is a derivative of the labor of building. The Ziv HaMishnah explains the Rambam's position, focusing on the words "for this is a labor performed by a physician" - i.e., one is not building a structure, but completing a specific labor that physicians perform. for this is a labor performed by a physician.
If one pierced it to remove its pus, [the act] is permitted.65I.e., one may perform the act without any compunctions (Shabbat 107a). Although the Rambam's ruling is quoted by the Shulchan Aruch (Orach Chayim 328:28), Shulchan Aruch HaRav 328:32 and the Mishnah Berurah 328:88 suggest that it is preferable to have this act performed by a gentile.
According to Rashi and many other authorities, this activity is permitted, because it is a מלאכה שאינה צריכה לגופה. Although generally there would be a Rabbinic prohibition against such an act, in this instance, no prohibition was enforced because of the suffering involved.
This explanation is, however, untenable for the Rambam, for as explained in Chapter 1, Halachah 7, he holds one liable for performing a מלאכה שאינה צריכה לגופה. Among the explanations given for the Rambam's position is that in removing the pus one does not complete the task involved, for an opening sufficient to be useful for another purpose has not been made (Maggid Mishneh). Similarly, Sefer HaBatim explains that in removing the pus, the person thinks only of relieving his pain and does not have any intent of making an opening. Thus the situation differs from the examples stated in Chapter 1, where the person performed the forbidden activity intentionally.
See also the commentary of Rav Chayim Soloveichik who explains that this decision is not dependent on the principle of מלאכה ש אינה צריכה לגופה, but rather on the concept of אינו מתכווין (see Chapter 1, Halachot 5-6) that a person who performs an activity which unintentionally causes a forbidden labor to be performed is not liable.
Although the Rambam agrees that when it is certain that one's actions will result in the performance of a forbidden labor, one is liable, the latter principle does not apply when one does not appreciate the results of the performance of the forbidden labor (פםיק רישא דלא ניחא ליה). In such an instance, the Rambam follows the opinion of the Aruch who maintains that one is not liable.

הלכה יח
הַמְסַתֵּת אֶת הָאֶבֶן כָּל שֶׁהוּא חַיָּב מִשּׁוּם מַכֶּה בְּפַטִּישׁ. הַמְצַדֵּד אֶת הָאֶבֶן בִּיסוֹד הַבִּנְיָן וְתִקְּנָהּ בְּיָדוֹ וְהוֹשִׁיבָהּ בַּמָּקוֹם הָרָאוּי לָהּ חַיָּב מִשּׁוּם מַכֶּה בְּפַטִּישׁ. הַלּוֹקֵט יַבּוֹלֶת שֶׁעַל גַּבֵּי בְּגָדִים בְּיָדוֹ כְּגוֹן אֵלּוּ הַיַּבּוֹלוֹת שֶׁבִּכְלֵי צֶמֶר חַיָּב מִשּׁוּם מַכֶּה בְּפַטִּישׁ. וְהוּא שֶׁיַּקְפִּיד עֲלֵיהֶן. אֲבָל אִם הֱסִירָן דֶּרֶךְ עֵסֶק הֲרֵי זֶה פָּטוּר. הַמְנַעֵר טַלִּית חֲדָשָׁה שְׁחוֹרָה כְּדֵי לְנָאוֹתָהּ וּלְהָסִיר הַצֶּמֶר הַלָּבָן הַנִּתְלֶה בָּהּ כְּדֶרֶךְ שֶׁהָאֻמָּנִין עוֹשִׂין חַיָּב חַטָּאת. וְאִם אֵינוֹ מַקְפִּיד מֻתָּר:
כסף משנה
18.
One who files a stone66Our translation is based on the Rambam's Commentary on the Mishnah (Shabbat 12:1), where he explains that this refers to "smoothing it with a tool known to be used for this purpose." Rashi (Shabbat 102b) renders this term as "chisel." to even the slightest degree is liable for performing [a derivative of] dealing [the final] hammer blow. A person who aligns a stone in the foundation of a building, adjusting its position with his hands and settling it in its proper place,67The Or Sameach (based on Shabbat 102b) states that this applies only in setting the stones of a building's foundation, and not those of its walls.
One might ask: Why is the person who performs this activity not liable for building (see Rashi and Tosafot, Shabbat, loc. cit.)? It is possible to explain that it goes without saying that the Rambam would hold such an individual liable for building, the new concept taught by this halachah is that he is also liable for dealing [the final] hammer blow.
is liable for performing [a derivative of] dealing [the final] hammer blow.
A person who removes threads, straws, or splinters of wood68Our translation is based on the commentary of Rabbenu Chanan'el on Shabbat 75b. from a garment by hand - for example, the splinters that are found in woolen garments - is liable for performing [a derivative of] dealing [the final] hammer blow. [This applies] provided the person is disturbed by them.69The Kessef Mishneh explains that this means that the person removes them from the garment with the intention of making it more attractive, even though he could wear the garment while they are still adhering to it. This interpretation is quoted by Shulchan Aruch HaRav 302:7 and the Mishnah Berurah 302:10. If, however, he removes them as a matter of course, [without thinking,]70As explained in Chapter 1, Halachah 11, a person is not liable for performing a forbidden activity as a מתעסק - i.e., without consciously controlling his behavior. In this instance as well, it is common for people to pick at their clothes, without giving the matter any thought at all. he is not liable.71It is, nevertheless, forbidden according to Rabbinic decree (Shulchan Aruch HaRav 302:6, Mishnah Berurah 302:11).
A person who shakes out a new black garment to make it attractive and to remove any remnants of white wool72The early manuscripts and printings of the Mishneh Torah state הציהוב הלבן. Based on the dictionary of Rabbi Tanchum of Jerusalem, this term is interpreted to mean "bright white threads." adhering to it, as is a tailor's practice,73Based on Shabbat 147a, the Ra'avad, Rashi, and others, interpret this as shaking dew from a new garment, and the activity being a derivative of the forbidden labor of whitening. This interpretation is accepted by the Shulchan Aruch (Orach Chayim 302:1). is liable to bring a sin offering.74Rav Sa'adiah Adana explains that according to the general principles the Rambam outlined in the beginning of the text, it would have been sufficient for him to state "is liable," as is his practice throughout the text. Nevertheless, in this instance he quotes the Sages' expression (Shabbat 147a), "is liable for a sin offering"; because of the nature of the activity, one might think that one is liable only for stripes for rebelliousness, the punishment given for violating a Rabbinic decree. If he is not disturbed by them, it is permissible [to do so].

הלכה יט
הַצָּד דָּבָר שֶׁדֶּרֶךְ מִינוֹ לָצוּד אוֹתוֹ חַיָּב. כְּגוֹן חַיָּה וְעוֹפוֹת וְדָגִים. וְהוּא שֶׁיָּצוּד אוֹתָן לְמָקוֹם שֶׁאֵינוֹ מְחֻסַּר צֵידָה. כֵּיצַד. כְּגוֹן שֶׁרָדַף אַחֲרֵי צְבִי עַד שֶׁהִכְנִיסוֹ לְבַיִת אוֹ לְגִנָּה אוֹ לְחָצֵר וְנָעַל בְּפָנָיו. אוֹ שֶׁהִפְרִיחַ אֶת הָעוֹף עַד שֶׁהִכְנִיסוֹ לְמִגְדָּל וְנָעַל בְּפָנָיו. אוֹ שֶׁשָּׁלָה דָּגִים מִן הַיָּם בְּתוֹךְ סֵפֶל שֶׁל מַיִם הֲרֵי זֶה חַיָּב. אֲבָל אִם הִפְרִיחַ צִפּוֹר לְבַיִת וְנָעַל בְּפָנָיו. אוֹ שֶׁהִבְרִיחַ דָּג וַעֲקָרוֹ מִן הַיָּם לִבְרֵכָה שֶׁל מַיִם. אוֹ שֶׁרָדַף אַחַר צְבִי עַד שֶׁנִּכְנַס לִטְרַקְלִין רָחָב וְנָעַל בְּפָנָיו הֲרֵי זֶה פָּטוּר. שֶׁאֵין זוֹ צִידָה גְּמוּרָה שֶׁאִם יָבוֹא לְקַחְתּוֹ צָרִיךְ לִרְדֹּף אַחֲרָיו וְלָצוּד אוֹתוֹ מִשָּׁם. לְפִיכָךְ הַצָּד אֲרִי אֵינוֹ חַיָּב עַד שֶׁיַּכְנִיסֶנּוּ לַכִּפָּה שֶׁלּוֹ שֶׁהוּא נֶאֱסָר בָּהּ:
כסף משנה
19.
A person who traps a living creature from a species that is common to trap75See Halachah 24, where the Rambam mentions some of the species not included in this category. - e.g., beasts, fowl,76The commentaries note that Shabbat 106b differentiates between a צפור דרור - a swallow - and other fowl. On this basis, the Shulchan Aruch (Orach Chayim 316:1) states that other birds are also considered trapped when enclosed in houses, and it is only a swallow - because it is small - that must be trapped in a closet.
The Merkevet HaMishneh and others explain that Rabbenu Yitzchak Alfasi and the Rambam interpret the conclusion of that Talmudic passage as indicating that there is no difference between one type of fowl and another. It is too difficult to trap any bird when enclosed in a house.
or fish - is liable77This is one of the 39 categories of forbidden labor. provided he traps them in a place where no further efforts are required to trap them.
What is implied? One chased after a deer until one caused it to enter a room,78The Hebrew בית usually means house. Here, however, it refers to a one-room structure. a garden, or a courtyard, and one locked it inside, one caused a fowl to fly into a closet and locked it, one removed a fish from the sea and placed it in a bowl of water. [In all these instances,] the person is liable.79The commentaries explain that a deer is trapped even when there are open windows and when there is no roof.
If, however, a person caused a bird to fly into a room and locked it, caused a fish to swim from the sea into a pool of water, or chased a deer until he caused it to enter a large hall, and locked it, he is not liable. [The living creature] is not completely trapped, for if he to desired to take it, he would have to chase it and trap it in [this new place].80See Hilchot Sh'vitat Yom Tov 2:7, where the Rambam develops this principle. Therefore, a person who traps a lion is not liable until he causes it to enter the pen in which it will be enclosed.

הלכה כ
כָּל מָקוֹם שֶׁאִם יָרוּץ בּוֹ יַגִּיעַ לַחַיָּה בִּשְׁחִיָּה אַחַת. אוֹ שֶׁהָיוּ הַכְּתָלִים קְרוֹבִין זֶה לָזֶה עַד שֶׁיִּפּל צֵל שְׁנֵיהֶם לָאֶמְצַע כְּאֶחָד הֲרֵי זֶה מָקוֹם קָטָן. וְאִם הִבְרִיחַ הַצְּבִי וְכַיּוֹצֵא בּוֹ לְתוֹכוֹ חַיָּב. וּמָקוֹם שֶׁהוּא גָּדוֹל מִזֶּה הַמַּבְרִיחַ חַיָּה וָעוֹף לְתוֹכוֹ פָּטוּר:
כסף משנה
20.
[The following] - a place in which if a person ran, he could reach the animal in a single movement,81The Maggid Mishneh states that this means "without having to pause." and a place so narrow that the shadow of both walls would merge in the middle - are considered to be small places. If one chased a deer or the like into such a place, one is liable. If a place is larger than this, a person who chases an animal or a fowl into it is not liable.

הלכה כא
אֶחָד שְׁמֹנָה שְׁרָצִים הָאֲמוּרִין בַּתּוֹרָה וְאֶחָד שְׁאָר שְׁקָצִים וּרְמָשִׂים שֶׁיֵּשׁ לְמִינָן צִידָה הַצָּד אֶחָד מִכֻּלָּן בֵּין לְצֹרֶךְ בֵּין שֶׁלֹּא לְצֹרֶךְ אוֹ לְשַׂחֵק בָּהֶן חַיָּב הוֹאִיל וְנִתְכַּוֵּן לָצוּד וְצָד. שֶׁמְּלָאכָה שֶׁאֵינָהּ צְרִיכָה לְגוּפָהּ חַיָּב עָלֶיהָ. הַצָּד אֶת הַיָּשֵׁן וְאֶת הַסּוּמָא חַיָּב:
כסף משנה
21.
[The following principle applies regarding] the eight creeping animals mentioned in the Torah82Leviticus 11:29. See Chapter 8, Halachah 9, for a definition of the species referred to. and similarly, other creeping animals and crawling things:83The distinction between the eight species mentioned in the Torah and other crawling animals is relevant within the context of the Mishnah, Shabbat 14:1, which follows the view of Rabbi Shimon that one is not held liable for performing a [forbidden] labor when he has no need for the actual labor he performed. Hence, it is necessary to differentiate between the eight species mentioned in the Torah (which are generally trapped for their hides) and other crawling animals when that is not necessarily the case. When a species is usually trapped, a person who traps any one of them - whether for a purpose, or without a purpose, even merely for the sake of sport - is liable, since he intended to trap and actually did so.84This ruling depends on the principle stated by the Rambam immediately afterwards, that one is held liable for performing a [forbidden] labor when he has no need for the actual labor he performed. A person is liable for performing a [forbidden] labor even if he has no need for the actual labor he performed.85This subject, referred to as a מלאכה שאינה צריכה לגופה in Hebrew, is discussed at length in Chapter 1, Halachah 7. As mentioned, there are many authorities who differ with the Rambam's opinion on this issue.
A person who traps an animal that is sleeping or a blind animal is liable.86As obvious from Halachah 24, a person who traps an animal that is physically disabled is not liable. Shabbat 106b differentiates between the animals mentioned in that halachah and those mentioned in this halachah as follows: An animal that is sleeping or blind is sensitive to man's steps. Unless he approaches stealthily, the animal will be startled and flee. In contrast, those mentioned in Halachah 24 will not be able to escape capture.

הלכה כב
הַמְשַׁלֵּחַ כְּלָבִים כְּדֵי שֶׁיָּצוּדוּ צְבָאִים וְאַרְנָבִים וְכַיּוֹצֵא בָּהֶן וּבָרַח הַצְּבִי מִפְּנֵי הַכֶּלֶב וְהָיָה הוּא רוֹדֵף אַחַר הַצְּבִי אוֹ שֶׁעָמַד בְּפָנָיו וְהִבְהִילוֹ עַד שֶׁהִגִּיעַ הַכֶּלֶב וּתְפָשׂוֹ הֲרֵי זֶה תּוֹלֶדֶת הַצָּד וְחַיָּב. וְכֵן הָעוֹשֶׂה כַּדֶּרֶךְ הַזּוֹ בְּעוֹפוֹת:
כסף משנה
22.
When a person sends out dogs to trap deer, rabbits, and the like, the deer flees because of the dog,87Note the Maggid Mishneh, who quotes Rabbenu Chanan'el's commentary, which explains this as a continuation of the concepts mentioned in the previous halachah. Rashi (Shabbat 106b) interprets the passage differently. (See the Be'ur Halachah 316.) and the person chases after the deer or stands before it and as such, frightens it so that the dog can catch it,88The Ramah (Orach Chayim 316:2) emphasizes that even during the week, this behavior is undesirable. In his Darchei Moshe, he emphasizes that such cruelty will prevent a person from participating in the feast of the Leviathan in the era of the redemption. he is liable for [performing] a derivative [of the forbidden labor] of trapping.89The Magen Avraham 316:4 emphasizes that if the person merely sends out the dogs and is not personally involved in the deer's capture, he is not held liable at all. There is, however, a Rabbinic prohibition involved. The same applies with regard to [trapping] fowl.

הלכה כג
צְבִי שֶׁנִּכְנַס לְבַיִת וְנָעַל אֶחָד בְּפָנָיו חַיָּב. נְעָלוּהוּ שְׁנַיִם פְּטוּרִין. אִם אֵין אֶחָד יָכוֹל לִנְעל וּנְעָלוּהוּ שְׁנַיִם חַיָּבִין. יָשַׁב אֶחָד עַל הַפֶּתַח וְלֹא מִלְּאָהוּ וְיָשַׁב הַשֵּׁנִי וּמִלְּאָהוּ הַשֵּׁנִי חַיָּב. יָשַׁב הָרִאשׁוֹן וּמִלְּאָהוּ וּבָא הַשֵּׁנִי וְיָשַׁב בְּצִדּוֹ אַף עַל פִּי שֶׁעָמַד הָרִאשׁוֹן וְהָלַךְ לוֹ הָרִאשׁוֹן חַיָּב וְהַשֵּׁנִי לֹא עָשָׂה כְּלוּם וּמֻתָּר לוֹ לֵישֵׁב בִּמְקוֹמוֹ עַד הָעֶרֶב וְלוֹקֵחַ הַצְּבִי. לְמָה זֶה דּוֹמֶה לְנוֹעֵל בֵּיתוֹ לְשָׁמְרוֹ וְנִמְצָא צְבִי שָׁמוּר בְּתוֹכוֹ שֶׁלֹּא עָשָׂה כְּלוּם. נִכְנְסָה לוֹ צִפּוֹר תַּחַת כְּנָפָיו יוֹשֵׁב וּמְשַׁמְּרָהּ עַד שֶׁתֶּחְשַׁךְ וּמֻתָּר:
כסף משנה
23.
When a deer enters a room and one person closes90Here, we have chosen to translate the Hebrew נעל as "close," rather than "lock." Closing the door is sufficient to confine the deer inside and cause one to be liable for trapping it. it, the latter is liable.91Although he did not actively pursue the deer into the room, since it becomes trapped through his deed, he is responsible. If two people close it, they are not liable. If the door cannot be closed by a single person and they both close it, they are both liable.92This halachah illustrates the principle stated in Chapter 1, Halachot 15- 16:

Whenever two people share in the performance of a [forbidden] labor that one of them could have performed by himself, they are [both] free of liability.... When, however, a single individual cannot perform [the forbidden labor] alone and must be joined by others, [all the individuals involved are held liable].

See Sefer HaKovetz and others for explanations why this is not a mere reiteration of the principles stated previously.

When one person sat in the entrance and did not block it, and a second person sat down and blocked it, the second person is liable.93The first person's act did not obstruct the deer's escape, while the second person's did. Although the first person assisted the second, since his assistance was passive - he did absolutely nothing - he does not share in the liability. Furthermore, as the Rambam states in his Commentary on the Mishnah (Shabbat 13:7), he is permitted to remain seated.
When the one person blocks the entrance when he sits down, and a second person sits down next to him [in a manner that also obstructs the entrance], the first person [alone] is liable.94For he completed the capture of the animal by sitting down. This is a fait acccompli to which the second person adds nothing. [This applies] even if he later rises and leaves, [and the second person remains blocking the entrance],95Without moving. for the second person has not done anything. He is permitted to remain seated in the doorway until the evening and then take the deer.96He may not, however, take the deer on the Sabbath itself. Although it is already trapped, it is muktzeh, forbidden to be handled. (See Chapter 25, Halachah 26.) To what could this be compared? To one who locks his house to protect it and finds a trapped deer inside.97In this instance, we have translated the Hebrew נע ל as "lock" rather than "close" as above. Were a person to close the door and thus trap the deer, he would be liable. The Rambam is speaking of a situation where the deer was trapped previously (in the analogy, by the first person) and then locked in (blocked further by the second person).
If a fowl enters under the edge of a person's clothes, he may [continue] sitting and watch it until nightfall.98In this instance as well, it is forbidden to take the bird on the Sabbath because it is muktzeh. It is [then] permitted [to take it].

הלכה כד
הַצָּד צְבִי זָקֵן אוֹ חִגֵּר אוֹ חוֹלֶה אוֹ קָטָן פָּטוּר. הַמְפָרֵק בְּהֵמָה חַיָּה וָעוֹף מִן הַמְּצוּדָה פָּטוּר. הַצָּד חַיָּה וָעוֹף שֶׁבִּרְשׁוּתוֹ כְּגוֹן אֲוָזִין וְתַרְנְגוֹלִין וְיוֹנֵי (עֲלִיָּה) פָּטוּר. הַצָּד דָּבָר שֶׁאֵין בְּמִינוֹ צִידָה כְּגוֹן חֲגָבִים הַגָּזִין צְרָעִין וְיַתּוּשִׁין וּפַרְעוֹשִׁין וְכַיּוֹצֵא בָּאֵלּוּ הֲרֵי זֶה פָּטוּר:
כסף משנה
24.
A person who traps a deer that is old, limping, sick, or small is not liable.99As explained in the notes on Halachah 21, one is not liable for trapping these creatures, because no real effort is required in doing so.
A person who releases an animal, a beast, or a fowl from a trap is not liable.100The Maggid Mishneh questions why the Rambam uses the term "is not liable," which implies that it is forbidden to do so by Rabbinic decree. What prohibition is there in releasing an animal from a trap? He answers that perhaps the intent is that the person is liable for violating the Rabbinic prohibition that deems an animal as muktzeh. Note the Magen Avraham 316:11 which states that one may release an animal or a fowl from a trap, provided one does not touch them. A person who traps a beast or a fowl that is in his domain - e.g., ducks, chickens, or doves from a cote - is not liable.101See Hilchot Sh'vitat Yom Tov 2:5, where the Rambam states that chickens and ducks are considered as within a person's grasp. Note, however, the distinction between the different types of doves mentioned in that halachah and in this halachah. Because of that difference, the Maggid Mishneh considers the mention of doves in this halachah as a printing error. Mention of them is found, however, in most early manuscripts and printings, and other authorities justify their mention. A person who traps a living being whose species is not usually trapped - e.g., locusts,102Rav Kapach states that this refers to non-kosher locusts. A person who catches kosher locusts is liable. The Mishnah Berurah 316:13, however, differs, and maintains that the Rambam does not hold one liable for trapping such species. wild bees, hornets, mosquitoes, fleas, and the like - is not liable.103Since it is not customary to trap these species, even a person who traps them for a specific purpose is not held liable (Shulchan Aruch HaRav 316:4). There is, however, a Rabbinic prohibition involved. For that reason, one must even take precautions not to trap such creatures accidentally (Ramah, Orach Chayim 316:3).

הלכה כה
רְמָשִׂים הַמַּזִּיקִין כְּגוֹן נְחָשִׁים וְעַקְרַבִּים וְכַיּוֹצֵא בָּהֶן אַף עַל פִּי שֶׁאֵינָן מְמִיתִין הוֹאִיל וְנוֹשְׁכִין מֻתָּר לָצוּד אוֹתָם בְּשַׁבָּת. וְהוּא שֶׁיִּתְכַּוֵּן לְהִנָּצֵל מִנְּשִׁיכָתָן. כֵּיצַד הוּא עוֹשֶׂה. כּוֹפֶה כְּלִי עֲלֵיהֶן אוֹ מַקִּיף עֲלֵיהֶן אוֹ קוֹשְׁרָן כְּדֵי שֶׁלֹּא יַזִּיקוּ:
כסף משנה
25.
Crawling beasts that are dangerous - e.g., snakes, scorpions and the like - may be trapped104I.e., not only is one not liable, but is permitted to do so. on the Sabbath. [This leniency is granted] even when they are not deadly, but merely bite, provided one's intent is to prevent [someone from] being bitten.105Most commentaries explain this ruling according to the opinions that do not hold one liable for performing a מלאכה שאינה צריכה לגופה. Although generally there would be a Rabbinic prohibition against such an act, in this instance no prohibition was enforced because of the danger involved.
This explanation is, however, untenable for the Rambam, for as explained in Chapter 1, Halachah 7, he follows Rabbi Yehudah's ruling that holds one liable for performing a מלאכה שאינה צריכה לגופה.
The Avnei Nezer (Likkutim 189) explains that this situation is different, because of the unique nature of the labor of trapping. The concept of trapping is relevant only when one traps an object of value. Therefore even Rabbi Yehudah frees one of liability when trapping an animal whose species is not usually trapped.
Similarly, in the instance at hand, since one has no concern for the object one is trapping, merely for one's personal welfare, the entire concept of trapping does not apply. See also the notes on Halachah 17 of this chapter and Chapter 11, Halachah 4.

What should one do? Place a utensil over them, cover them with something, or tie them so they cannot cause damage.

זמנים הלכות שבת פרק י
Zemanim Shabbos Chapter 10