Halacha

הלכה א
אָדָם שֶׁנִּטְמָא בְּמֵת וְהִזָּה עָלָיו כֵּיוָן שֶׁנָּגַע כָּל שֶׁהוּא מִמֵּי הַנִּדָּה בְּכָל מָקוֹם מֵעוֹר בְּשָׂרוֹ שֶׁל טָמֵא עָלְתָה לוֹ הַזָּיָה. אֲפִלּוּ נָפְלָה הַהַזָּאָה עַל רֹאשׁ אֶצְבָּעוֹ אוֹ עַל רֹאשׁ שְׂפָתוֹ. אֲבָל אִם נָגְעָה בִּלְשׁוֹנוֹ אֵינָהּ כְּלוּם. אַף עַל פִּי שֶׁהַלָּשׁוֹן כְּאֵיבָרִים שֶׁבְּגָלוּי לְעִנְיַן טֻמְאָה כְּמוֹ שֶׁבֵּאַרְנוּ. אֵינָן כְּאֵיבָרִים שֶׁבְּגָלוּי לְעִנְיַן הַזָּאָה וּטְבִילָה. וְכֵן כְּלִי שֶׁנִּטְמָא בְּמֵת וְהִזָּה עָלָיו כֵּיוָן שֶׁהִגִּיעַ לְגוּפוֹ שֶׁל כְּלִי כָּל שֶׁהוּא מִמֵּי הַנִּדָּה עָלְתָה לוֹ הַזָּאָה:
כסף משנה
1.
When the water of the ashes of the red heifer was sprinkled on a person who became impure due to contact with a human corpse, if even the slightest amount of the water touches any portion of the body of the impure person, the sprinkling is effective. This applies even if the sprinkling fell on the tips of his fingers or on the tip of his lips. If, however, the water touched his tongue, it is of no consequence. Even though the tongue is considered as a revealed organ with regard to contracting ritual impurity, as we explained, it is not considered as one of the revealed organs with regard to sprinkling and immersion.
Similarly, when a k'li contracted impurity from a corpse and the water was sprinkled on it, if even the slightest amount of the sprinkling water touches the body of the k'li, the sprinkling is effective.

הלכה ב
שְׁנֵי כֵּלִים אוֹ שְׁנֵי בְּנֵי אָדָם שֶׁנִּתְכַּוֵּן לְהַזּוֹת עַל שְׁנֵיהֶן כְּאַחַת וְהִזָּה עַל אֶחָד מֵהֶן. וְנָטְפוּ הַמַּיִם מֵעַל הָרִאשׁוֹן עַל הַשֵּׁנִי הֲרֵי הַשֵּׁנִי בְּטֻמְאָתוֹ עַד שֶׁיִּפְּלוּ עָלָיו הַמַּיִם מֵהַזָּיַת הַמַּזֶּה לֹא מִן הַתַּמְצִית. הִזָּה עַל שְׁנֵי כֵּלִים וְנִסְתַּפֵּק לוֹ אִם הִזָּה עַל שְׁנֵיהֶן כְּאַחַד אוֹ מֵחֲבֵרוֹ נִמְצָה עָלָיו הַזָּיָתוֹ פְּסוּלָה:
כסף משנה
2.
When one intended to sprinkle on two keilim or two people at the same time and one sprinkled water on one of them and then it dripped from the first to the second, the second remains impure until water falls upon him from the sprinkling and not from the concentration of water in another place.
If one sprinkled on two keilim and one was in doubt whether he sprinkled on both at once or the water dripped from one to the other, the sprinkling is invalid.

הלכה ג
מַחַט שֶׁנְּתוּנָה עַל הַחֶרֶשׂ וְהִזָּה עָלֶיהָ סָפֵק עַל הַמַּחַט הִזָּה סָפֵק מִן הַחֶרֶשׂ נִמְצָה עָלֶיהָ הַזָּיָתוֹ פְּסוּלָה:
כסף משנה
3.
When a needle was placed on a shard and one intended to sprinkle water on it, but a doubt arose whether he sprinkled on the needle or the water dripped on it from the shard, the sprinkling is invalid.

הלכה ד
כֵּלִים הַמְפֻצָּלִין שֶׁמְּחֻבָּרִין זֶה לָזֶה בְּמַסְמְרִים. כְּגוֹן מִסְפֹּרֶת שֶׁל פְּרָקִים וְאִזְמֵל שֶׁל רְהִיטְנִי וְכַיּוֹצֵא בָּהֶן. בִּשְׁעַת מְלָאכָה חִבּוּר לְטֻמְאָה וּלְהַזָּיָה. שֶׁלֹּא בִּשְׁעַת מְלָאכָה אֵינוֹ חִבּוּר לֹא לָזֶה וְלֹא לָזֶה. כֵּיצַד הֵן חִבּוּר לְטֻמְאָה וּלְהַזָּיָה. שֶׁאִם נִטְמָא אֶחָד מֵהֶן בִּשְׁעַת מְלָאכָה נִטְמָא הַשֵּׁנִי. וְאִם הִזָּה עַל אֶחָד מֵהֶן בִּשְׁעַת מְלָאכָה עָלְתָה הַזָּיָה לִשְׁנֵיהֶן וּכְאִלּוּ הֵן גּוּף אֶחָד. וְכֵיצַד אֵינוֹ חִבּוּר לֹא לְטֻמְאָה וְלֹא לְהַזָּיָה. שֶׁאִם נִטְמָא אֶחָד מֵהֶן שֶׁלֹּא בִּשְׁעַת מְלָאכָה לֹא נִטְמָא חֲבֵרוֹ. וְאִם נִטְמְאוּ שְׁנֵיהֶן וְהִזָּה עַל אֶחָד מֵהֶן שֶׁלֹּא בִּשְׁעַת מְלָאכָה לֹא טִהֵר חֲבֵרוֹ אַף עַל פִּי שֶׁהֵן מְחֻבָּרִין. וְזֶהוּ דִּין תּוֹרָה. אֲבָל מִדִּבְרֵי סוֹפְרִים גָּזְרוּ שֶׁיִּהְיוּ חִבּוּר לְטֻמְאָה אֲפִלּוּ שֶׁלֹּא בִּשְׁעַת מְלָאכָה גְּזֵרָה מִשּׁוּם שְׁעַת מְלָאכָה. וּלְעוֹלָם אִם נָגְעָה בְּאֶחָד מֵהֶן טֻמְאָה נִטְמָא חֲבֵרוֹ. וְכֵן גָּזְרוּ עֲלֵיהֶן שֶׁלֹּא יִהְיוּ חִבּוּר לְהַזָּיָה אֲפִלּוּ בִּשְׁעַת מְלָאכָה גְּזֵרָה מִשּׁוּם שֶׁלֹּא בִּשְׁעַת מְלָאכָה. וּלְעוֹלָם אִם הִזָּה עַל אֶחָד מֵהֶן לֹא טִהֵר חֲבֵרוֹ עַד שֶׁיַּזֶּה גַּם עָלָיו. הִנֵּה לָמַדְתָּ שֶׁכָּל מָקוֹם שָׁאַתָּה שׁוֹמֵעַ חִבּוּר לְטֻמְאָה וְאֵינוֹ חִבּוּר לְהַזָּיָה אֵין זֶה אֶלָּא גְּזֵרָה מִדִּבְרֵיהֶם עַל הַדֶּרֶךְ שֶׁבֵּאַרְנוּ:
כסף משנה
4.
The following laws apply when there are keilim that have several parts which are connected to each other with nails, e.g., a scissors that comes apart, the blade of a plane, or the like. At the time of work, they are considered as joined, with regard to both impurity and sprinkling. When work is not being performed with them, neither is considered as joined to the other.
What is meant by saying that they are considered as joined, with regard to both impurity and sprinkling? That if one of the parts contracts impurity at the time work is being performed, the second also contracts impurity. Conversely, if water was sprinkled on one while work was being performed with them, the sprinkling is also effective with regard to the other and it is as if they are a single entity.
What is meant by saying that they are not considered as joined, with regard to both impurity and sprinkling? That if one contracts impurity while work is not being performed with it, the other does not contract impurity. And if both had contracted impurity and one sprinkled the water on one at a time when work was not being performed, the other does not become pure, even though they were joined together at that time.
This is the Scriptural Law. According to Rabbinic Law, however, it was decreed that they should be considered as joined with regard to impurity even at a time when work was not being performed. This decree was instituted as a safeguard for the law applying when work was being performed. Whenever impurity touches one of them, the other also becomes impure.
They also decreed that they should not be considered as joined with regard to sprinkling, even at a time when work was being performed. This decree was instituted as a safeguard for the law applying when work was not being performed. Whenever one sprinkles the water on one of them, the other does not regain purity until the water is also sprinkled on the other. From this, it can be inferred that whenever it is mentioned that two entities are considered as joined with regard to impurity, but not with regard to sprinkling, this is merely a Rabbinic decree, following the pattern explained above.

הלכה ה
שְׁנֵי כֵּלִים שֶׁחִבְּרָן עַד שֶׁנַּעֲשׂוּ כְּגוּף אֶחָד. כְּגוֹן שֶׁתָּפַר שְׁנֵי בְּגָדִים אוֹ שְׁתֵּי יְרִיעוֹת הֲרֵי אֵלּוּ חִבּוּר לְטֻמְאָה וּלְהַזָּאָה מִפְּנֵי שֶׁהֵן כִּכְלִי אֶחָד:
כסף משנה
5.
When two articles are joined together to the extent that they are considered as a single entity, e.g., one sewed together two garments or two parchments, they are considered as joined for both impurity and sprinkling, because they are a single entity.

הלכה ו
שְׁלַל הַכּוֹבְסִין וְהַבֶּגֶד שֶׁהוּא תָּפוּר בְּכִלְאַיִם וְהֵן עוֹמְדִין לְהַתִּירָן אֵינוֹ חִבּוּר לְהַזָּיָה וַהֲרֵי הֵן חִבּוּר לְטֻמְאָה. וְכֵן הַסְּלָעִים שֶׁבַּקַּנְתָּל. וְהַמִּטָּה שֶׁל טַרְבָּל. וְקֶרֶן שֶׁל כְּלִיבָה. וְקַרְנַיִם שֶׁל יוֹצְאֵי דְּרָכִים. וְשַׁלְשֶׁלֶת הַמַּפְתְּחוֹת. חִבּוּר לְטֻמְאָה וְלֹא לְהַזָּאָה. אֶלָּא צָרִיךְ שֶׁיִּגְּעוּ הַמַּיִם מִן הַמַּזֶּה בְּכָל סַל וְסַל. וּבְכָל מַפְתֵּחַ וּמַפְתֵּחַ. וּבְכָל קֶרֶן וְקֶרֶן. וּבְכָל קוֹרָה וְקוֹרָה מִמִּטָּה זוֹ הַמְפֻצֶּלֶת:
כסף משנה
6.
A launderer's sewing and a garment that is sewn with a forbidden mixture of fabrics that are about to be separated are not considered as joined with regard to sprinkling, but are considered as joined with regard to impurity.
Baskets joined as a carrier, a threshing utensil, the feet of a bed, drinking horns of travelers, and a chain of keys, are considered as joined with regard to impurity, but are not considered as joined with regard to sprinkling. Instead, the water that is sprinkled must reach each individual basket, each individual key, each individual horn, and every beam of the bed that is assembled.

הלכה ז
הַמְחַבֵּר שָׁלֹשׁ כְּסָתוֹת שֶׁל צֶמֶר וְשֵׁשׁ שֶׁל פִּשְׁתָּן. אוֹ שְׁלֹשָׁה סְדִינִים אוֹ שְׁתֵּים עֶשְׂרֵה מִטְפָּחוֹת. הֲרֵי אֵלּוּ חִבּוּר לְטֻמְאָה וּלְהַזָּאָה. יֶתֶר מִכָּאן חִבּוּר לְטֻמְאָה וְלֹא לְהַזָּאָה. חָלוּק אֶחָד וְטַלִּית אַחַת וּקְלוּבְקָרִין אֶחָד הֲרֵי הֵן חִבּוּר לְטֻמְאָה וּלְהַזָּיָה אֲפִלּוּ הָיוּ אֲרֻכִּין בְּיוֹתֵר אוֹ רְחָבִין בְּיוֹתֵר כָּל שֶׁהֵן. וְאֵי זֶהוּ קְלוּבְקָרִין זֶה שְׁנֵי בְּגָדִים שֶׁמַּנִּיחִין צֶמֶר גֶפֶן בֵּינֵיהֶן וְתוֹפְרִין אוֹתָן כְּאַחַת וְעוֹשִׂין מֵהֶן חָלוּק לִימוֹת הַגְּשָׁמִים:
כסף משנה
7.
When a person joins three blankets of wool or six of linen or three sheets or twelve kerchiefs, they are considered as joined with regard both to impurity and sprinkling. Any more than the above quantities are considered as joined with regard to impurity, but are not considered as joined with regard to sprinkling. One cloak, one garment, and one klubkerin, are considered as joined with regard to impurity and sprinkling, even if they are very long or very wide, no matter how large they are.
What is a klubkerin? Two garments are taken. Cotton is placed between them as a lining and then they are sewn together as one and worn as an outer garment for the winter.

הלכה ח
כִּסּוּי הַמֵּחַם שֶׁמְּחֻבָּר בְּשַׁלְשֶׁלֶת. הִזָּה עַל הַמֵּחַם טִהֵר הַכּל. הִזָּה עַל הַכִּסּוּי לֹא טִהֵר הַמֵּחַם עַד שֶׁיַּזֶּה עָלָיו:
כסף משנה
8.
When the covering of a samovar is connected by chains, when one sprinkles on the samovar, everything is purified. If one sprinkled on the cover, one did not purify the samovar. It is necessary to sprinkle on it directly.

הלכה ט
הַזּוֹג וְהָעִנְבָּל חִבּוּר לְטֻמְאָה וּלְהַזָּאָה וְאִם הִזָּה עַל אֶחָד מֵהֶן טִהֲרוּ שְׁנֵיהֶן:
כסף משנה
9.
A bell and its clanger are considered as joined with regard both to impurity and sprinkling. If one sprinkled on one of them, they both regain their purity.

הלכה י
הַטֶּוִוי שֶׁטּוֹוִים בּוֹ הַפִּשְׁתִּים אוֹ שׁוֹזְרִין בּוֹ הַחֲבָלִים שְׁלֹשָׁה גּוּפִין יֵשׁ בּוֹ. הָעֵץ שֶׁמְּלַפְּפִין עָלָיו הַטָּווּיִ וְהוּא הַנִּקְרָא כּוּשׁ. וְהַנְּחשֶׁת אוֹ הַבַּרְזֶל שֶׁבְּרֹאשׁ הָעֵץ וְהוּא הַנִּקְרָא צִנּוֹרָא שֶׁבָּהּ פּוֹתְלִין וְטוֹוִין. וְהָרֵחַיִם שֶׁבְּאֶמְצַע הַכּוּשׁ וְהִיא הַנִּקְרֵאת פִּיקָא. הַכּוּשׁ שֶׁפּוֹתְלִין בּוֹ הַחֲבָלִים שֶׁנִּטְמָא לֹא יַזֶּה עַל הַפִּיקָא שֶׁלּוֹ וְלֹא עַל הַכּוּשׁ אֶלָּא עַל הַצִּנּוֹרָא. וְאִם הִזָּה עַל אֶחָד מִשְּׁלָשְׁתָּן טִהֵר הַכּל. וְשֶׁל פִּשְׁתָּן מַזֶּה עַל אֶחָד מִשְּׁלָשְׁתָּן לְכַתְּחִלָּה שֶׁשְּׁלָשְׁתָּן חִבּוּר:
כסף משנה
10.
A spindle on which flax is spun or ropes are made is composed of three parts: a) the rod around which the thread is wound; it is called a kush;
b) the copper or iron hook at the top of the rod with which one spins and makes threads; it is called a tzinorah;
c) the ball that is in the center of the rod; it is called the pika.
When the spindle on which ropes are wound becomes impure, one should not sprinkle on the pika or the kush, only on the tzinora. After the fact, if one sprinkled on one of the three, everything is purified. If a spindle is used for flax, one may sprinkle on any of the three as an initial preference, for the three are joined together.

הלכה יא
עוֹר שֶׁל עֲרִיסָה שֶׁהוּא מְחֻבָּר לְפִיקוֹת. חִבּוּר לְטֻמְאָה וּלְהַזָּאָה. הַמַּלְבֵּן שֶׁל מִטּוֹת אֵינוֹ חִבּוּר לֹא לְטֻמְאָה וְלֹא לְהַזָּאָה:
כסף משנה
11.
A piece of leather used to cover a cradle that is connected by buttons is considered as joined with regard both to impurity and sprinkling. The wooden frame placed on top of a bed is not considered as joined, neither with regard to impurity, nor with regard to sprinkling.

הלכה יב
כָּל יְדוֹת הַכֵּלִים הַקְּדוּחוֹת כְּגוֹן נִצַּב הַסַּכִּין וְכַיּוֹצֵא בּוֹ שֶׁהַנִּצָּב נָקוּב וְהַבַּרְזֶל נִכְנָס בּוֹ חִבּוּר לְטֻמְאָה וּלְהַזָּאָה. אֲבָל הַיָּדוֹת הַחֲרוּקוֹת כְּגוֹן עֵץ הַחֲנִית שֶׁהָעֵץ נִכְנָס בַּבַּרְזֶל אֵינוֹ חִבּוּר לְהַזָּאָה:
כסף משנה
12.
All of the hollow handles of keilim - e.g., a knife handle and the like, i.e., the handle has an opening and the iron shaft enters it - are considered as joined with regard both to impurity and sprinkling. All protruding handles - e.g., the handle of a javelin in which a portion of the wood is inserted into the iron shaft - are not considered as joined with regard to sprinkling.

טהרה הלכות פרה אדומה פרק יב
Taharah Para Aduma Chapter 12