Halacha

הלכה א
קוֹרוֹת וַאֲבָנִים וְעֵצִים וְכַיּוֹצֵא בָּהֶן שֶׁשְּׁטָפָם הַנָּהָר אִם נִתְיָאֲשׁוּ הַבְּעָלִים מֵהֶן הֲרֵי אֵלּוּ מֻתָּרִין וְהֵן שֶׁל מַצִּילָן. וְאִם אֵינוֹ יוֹדֵעַ אִם נִתְיָאֲשׁוּ אִם לֹא נִתְיָאֲשׁוּ חַיָּב לְהַחְזִיר. וְאֵין צָרִיךְ לוֹמַר אִם הָיוּ הַבְּעָלִים מְרַדְּפִין אַחֲרֵיהֶן:
כסף משנה
1.
The following rules apply when a river washes away beams, stones, wood and the like. If the owners despaired of their return, it is permitted for the finder to keep them, and they become his property. If, however, the finder does not know whether or not the owners have despaired, he is obligated to return the objects. Needless to say, this applies if the owners are pursuing the article.

הלכה ב
לְפִיכָךְ הַמַּצִּיל מִן הַנָּהָר וּמִזּוּטוֹ שֶׁל יָם וּמִשְּׁלוּלִיתוֹ שֶׁל נָהָר וּמִן הָעַכּוּ''ם וּמִן הַדְּלֵקָה וּמִן הָאֲרִי וּמִן הַדֹּב וּמִן הַנָּמֵר וּמִן הַבַּרְדְּלָס. אִם יָדַע בְּוַדַּאי שֶׁנִּתְיָאֲשׁוּ הַבְּעָלִים הֲרֵי אֵלּוּ שֶׁלּוֹ. וְאִם לֹא יָדַע יַחְזִיר:
כסף משנה
2.
Therefore, the same principle is applied when a person saves an article from the bed of a sea, from a flooding river, from gentiles, from a fire, from a lion, from a bear, from a tiger or from a leopard. If one knows that the owners have despaired of the article's return, it may be kept by the finder. If one does not know, one must return it.

הלכה ג
הַמַּצִּיל מִיַּד לִסְטִים יִשְׂרָאֵל הֲרֵי אֵלּוּ שֶׁלּוֹ מִפְּנֵי שֶׁסְּתָם הַדָּבָר שֶׁנִּתְיָאֲשׁוּ הַבְּעָלִים. וְאִם יָדַע שֶׁלֹּא נִתְיָאֲשׁוּ חַיָּב לְהַחְזִיר. אֲבָל הַמַּצִּיל מִיַּד לִסְטִים עוֹבֵד כּוֹכָבִים אוֹ מוֹכֵס עַכּוּ''ם חַיָּב לְהַחְזִיר שֶׁסְּתָם הַדָּבָר שֶׁלֹּא נִתְיָאֲשׁוּ הַבְּעָלִים. וְאִם יָדַע בְּוַדַּאי שֶׁנִּתְיָאֲשׁוּ הֲרֵי אֵלּוּ שֶׁלּוֹ. וּמִפְּנֵי מָה סְתָם לִסְטִים יִשְׂרָאֵל נִתְיָאֲשׁוּ הַבְּעָלִים וּסְתָם הָעַכּוּ''ם לֹא נִתְיָאֲשׁוּ. מִפְּנֵי שֶׁהַבְּעָלִים יוֹדְעִים שֶׁהָעַכּוּ''ם מַחֲזִירִין מִיַּד הַגַּזְלָן אַף עַל פִּי שֶׁאֵין שָׁם עֵדִים שֶׁגָּזַל אֶלָּא בִּרְאָיוֹת רְעוּעוֹת וּבְאֹמֶד הַדַּעַת:
כסף משנה
3.
When a person saves an article from a Jewish robber, he may keep it, for we assume that the owners despaired of its return. If, however, he knows that they did not despair of its return, he is obligated to return it.
When, by contrast, a person saves an article from a gentile robber, he is obligated to return it, for we do not assume that the owners despaired of its return. If, however, he knows that they did despair of its return, he may keep it.
Why do we say with regard to Jewish robbers that we can assume that the owners despair, while with regard to gentile robbers we do not assume that they despair? Because the owners know that the gentile authorities will require a robber to return an article obtained by robbery, although there are no witnesses that he committed robbery. Circumstantial evidence and probability are sufficient.

הלכה ד
שַׁחֲלַיִים הַצּוֹמְחִים בְּתוֹךְ הַפִּשְׁתָּן הַמְלַקְּטָן כְּשֶׁהֵן לַחִין אֵין בּוֹ מִשּׁוּם גֵּזֶל מִפְּנֵי שֶׁהֵן מַפְסִידִין הַפִּשְׁתָּן שֶׁל בַּעַל הַשָּׂדֶה. וְאִם יָבְשׁוּ אֲסוּרִין מִשּׁוּם גֵּזֶל שֶׁכְּבָר הִפְסִידוּ מַה שֶּׁהִפְסִידוּ. וְאִם הָיוּ עַל הַגְּבוּל אֲסוּרִין אֲפִלּוּ כְּשֶׁהֵן לַחִין:
כסף משנה
4.
It is not considered robbery to take fresh cress that grows among flax, because it harms the flax belonging to the owner of the field. If the cress has become dry, taking it is considered robbery, because it has already caused whatever damage it might cause.
If it grows on the border of the rows of flax, it is forbidden to be taken even if it is fresh.

הלכה ה
כְּבָר בֵּאַרְנוּ בְּנִזְקֵי מָמוֹן שֶׁהַמּוֹצִיא תִּבְנוֹ וְקַשּׁוֹ לִרְשׁוּת הָרַבִּים אֵין בָּהֶם מִשּׁוּם גֵּזֶל. אֲבָל הַמּוֹצִיא הַגָּלָל לִרְשׁוּת הָרַבִּים בֵּין בִּשְׁעַת הוֹצָאַת זְבָלִים בֵּין שֶׁלֹּא בִּשְׁעַת הוֹצָאַת זְבָלִים חַיָּבִין עֲלֵיהֶם מִשּׁוּם גֵּזֶל:
כסף משנה
5.
We have stated in Hilchot Nizkei Mammon that taking straw and hay that a person has placed in the public domain is not considered robbery. If, however, a piece of feces is placed in the public domain, whether during the time when taking out wastes is permitted or at other times, taking it is considered to be robbery.

הלכה ו
מִי שֶׁנִּתְחַלְּפוּ לוֹ כֵּלָיו בְּכֵלִים אֲחֵרִים בְּבֵית הָאָבֶל אוֹ בְּבֵית הַמִּשְׁתֶּה הֲרֵי זֶה לֹא יִשְׁתַּמֵּשׁ בָּהֶן עַד שֶׁיָּבוֹא הַלָּה וְיַחְזִיר וְיִטּל אֶת שֶׁלּוֹ. נִתְחַלְּפוּ לוֹ בְּבֵית הָאֻמָּן אִם אִשְׁתּוֹ וּבָנָיו שֶׁל אֻמָּן נָתְנוּ לוֹ אוֹ שֶׁנָּתַן לוֹ הָאֻמָּן וְאָמַר לוֹ טֹל כֵּלֶיךָ הֲרֵי זֶה לֹא יִשְׁתַּמֵּשׁ בָּהֶן עַד שֶׁיָּבוֹא הַלָּה וְיַחְזִיר וְיִטּל אֶת שֶׁלּוֹ. אָמַר לוֹ הָאֻמָּן טֹל כְּלִי זֶה הֲרֵי זֶה יִשְׁתַּמֵּשׁ בּוֹ עַד שֶׁיָּבוֹא הַלָּה וְיַחְזִיר וְיִטּל אֶת שֶׁלּוֹ שֶׁמָּא כֵּלָיו שֶׁל אֻמָּן הוּא אוֹ בַּעַל הַכְּלִי צִוָּה אֶת הָאֻמָּן לְמָכְרוֹ לוֹ. וְכֵן כָּל כַּיּוֹצֵא בָּזֶה:
כסף משנה
6.
When a person's clothes were exchanged for those belonging to another person at a house of mourning or a place of celebration, he should not use the article in his possession unless the owner comes and returns the original article and takes his own.
Slightly different rules apply if a person's articles become exchanged for another's in the home of a craftsman. If the craftsman's wife or children gave him the articles, or the craftsman gave him the articles and told him: "Take your articles," the person should not use the articles in his possession unless the owner comes and returns the original articles and takes his own.
If, however, the craftsman tells him: "Take this article," he may use it until the owner comes and returns the original articles and takes his own. For it is possible that the article belongs to the craftsman, or that the owner of the article told the craftsman to sell it for him. Similar laws apply in all analogous situations.

הלכה ז
דְּבָרִים הַרְבֵּה אָסְרוּ חֲכָמִים מִשּׁוּם גֵּזֶל וְהָעוֹבֵר עֲלֵיהֶן הֲרֵי זֶה גַּזְלָן מִדִּבְרֵיהֶם. כְּגוֹן מַפְרִיחֵי יוֹנִים וְהַמְשַׂחֲקִים בְּקֻבִּיָּא. מַפְרִיחֵי יוֹנִים כֵּיצַד. לֹא יַפְרִיחַ אָדָם בְּתוֹךְ הַיִּשּׁוּב שֶׁהֲרֵי לוֹקֵחַ מָמוֹן אֲחֵרִים שֶׁלֹּא כַּדִּין מִפְּנֵי שֶׁמְּשַׁלֵּחַ זָכָר וְיָבִיא נְקֵבָה מִשּׁוֹבָךְ אַחֵר אוֹ נְקֵבָה וְתָבִיא זָכָר. וְלֹא יוֹנִים בִּלְבַד אֶלָּא כָּל הָעוֹשֶׂה כָּזֶה בִּשְׁאָר עוֹפוֹת אוֹ חַיָּה וּבְהֵמָה הֲרֵי זֶה גַּזְלָן מִדִּבְרֵיהֶם:
כסף משנה
7.
Our Sages forbade many acts, classifying them as robbery - e.g., one who sets doves into flight or plays dice. If a person transgresses these prohibitions, he is considered a robber by Rabbinic decree.
What is meant by setting doves into flight? A person should not set doves into flight in a settled area, because he will take property belonging to others unjustly. For he will send out a male and it will bring a female from another dovecote; he will send out a female and it will bring a male.
This does not apply to doves alone. Instead, anyone who performs a like act with regard to other fowl, beasts or domesticated animals is considered to be a robber by Rabbinic decree.

הלכה ח
וְכֵן אָסְרוּ חֲכָמִים לָצוּד יוֹנִים בְּתוֹךְ הַיִּשּׁוּב מִפְּנֵי שֶׁהֵן שֶׁל אֲחֵרִים. וְאֵין פּוֹרְשִׂין נִישׁוֹבִין לְיוֹנִים אֶלָּא אִם כֵּן הִרְחִיק מִן הַיִּשּׁוּב אַרְבָּעָה מִילִין. וְאִם הָיָה יִשּׁוּב כְּרָמִים אֲפִלּוּ מֵאָה מִיל לֹא יִפְרשֹׁ שֶׁהַיּוֹנִים שֶׁל בַּעֲלֵי כְּרָמִים הֵם. וְכֵן לֹא יִפְרשֹׁ בְּתוֹךְ הַשּׁוֹבָכִין אַף עַל פִּי שֶׁהֵן שֶׁלּוֹ אוֹ שֶׁל עַכּוּ''ם אוֹ שֶׁל הֶפְקֵר וְאַף עַל פִּי שֶׁהִרְחִיק מִן הַיִּשּׁוּב מֵאָה מִיל מִפְּנֵי שֶׁהַיּוֹנִים בָּאוֹת לְיִשּׁוּב הַשּׁוֹבָכִין:
כסף משנה
8.
Similarly, our Sages forbade snaring doves within a settled area, for we can assume that the doves belong to others. One may not set a snare for doves unless one places a distance of four mil between the snare and the settled area. Moreover, if the settled area is composed of vineyards, one should not set a snare even within 100 mil, for the doves belong to the owners of the vineyards.
Similarly, a person should not set a snare among dovecotes even if he owns those dovecotes, or they belong to a gentile or are ownerless, even if the dovecotes are more than 100 mil from the settled area, for the doves from the settled area will come to the area of the dovecotes.

הלכה ט
מַרְחִיקִין אֶת הַשּׁוֹבָךְ מִן הָעִיר חֲמִשִּׁים אַמָּה. וְלֹא יַעֲשֶׂה אָדָם שׁוֹבָךְ בְּתוֹךְ שָׂדֵהוּ אֶלָּא אִם כֵּן יֵשׁ לוֹ חֲמִשִּׁים אַמָּה לְכָל רוּחַ כְּדֵי שֶׁלֹּא יִמָּשְׁכוּ הַגּוֹזָלוֹת וְיַפְסִידוּ בַּשָּׂדוֹת וְיֹאכְלוּ מִשֶּׁל אֲחֵרִים. וְאִם לְקָחוֹ מֵאַחֵר אֲפִלּוּ הָיָה בֵּינוֹ וּבֵין תְּחִלַּת שְׂדֵה חֲבֵרוֹ בֵּית רֹבַע בִּלְבַד הֲרֵי הוּא בְּחֶזְקָתוֹ וְאֵין מְחַיְּבִין אוֹתוֹ לְהַרְחִיק:
כסף משנה
9.
When constructing a dovecote, a person should position it at least 50 cubits from the village. Similarly, a person should not construct a dovecote in his field unless he owns the property in a radius of 50 cubits on all sides, so the doves will not be drawn forth and damage the fields of others by eating their produce.
If a person purchased a dovecote from another person, he may continue using it even if there is only a distance in which a quarter of a kav of grain can be sown between the dovecote and the beginning of his colleague's field. We do not require him to move it further away.

הלכה י
הַמְשַׂחֲקִין בְּקֻבִּיָּא כֵּיצַד. אֵלּוּ שֶׁמְּשַׂחֲקִין בְּעֵצִים אוֹ בִּצְרוֹרוֹת אוֹ בַּעֲצָמוֹת וְכַיּוֹצֵא בָּהֶן וְעוֹשִׂים תְּנַאי בֵּינֵיהֶם שֶׁכָּל הַנּוֹצֵחַ אֶת חֲבֵרוֹ בְּאוֹתוֹ שְׂחוֹק יִקַּח מִמֶּנּוּ כָּךְ וְכָךְ הֲרֵי זֶה גֵּזֶל מִדִּבְרֵיהֶם. אַף עַל פִּי שֶׁבִּרְצוֹן הַבְּעָלִים לָקַח הוֹאִיל וְלָקַח מָמוֹן חֲבֵרוֹ בְּחִנָּם דֶּרֶךְ שְׂחוֹק וְהִתּוּל הֲרֵי זֶה גּוֹזֵל. וְכֵן הַמְשַׂחֲקִים בִּבְהֵמָה אוֹ בְּחַיָּה אוֹ בְּעוֹפוֹת וְעוֹשִׂים תְּנַאי שֶׁכָּל שֶׁתְּנַצֵּחַ בְּהֶמְתּוֹ אוֹ תָּרוּץ יוֹתֵר יִקַּח מֵחֲבֵרוֹ כָּךְ וְכָךְ וְכָל כַּיּוֹצֵא בִּדְבָרִים אֵלּוּ הַכּל אָסוּר וְגֵזֶל מִדִּבְרֵיהֶם הוּא:
כסף משנה
10.
What is meant by dice players? People who play with pieces of wood, pebbles, bones or the like and establish a condition that whoever will better a colleague in this sport is entitled to take a certain amount of money from him. This is robbery according to Rabbinic decree. Although the person himself consents to the other person's taking his money, since he is taking it for nothing, as part of the frivolous sport, it is considered to be robbery.
Similarly, those who gamble with regard to domesticated animals, beasts or fowl, making a condition that whosoever's animal will vanquish or outrace the other one's is entitled to take a certain amount of money from him - this and all forms of gambling are forbidden and considered to be robbery by Rabbinic decree.

הלכה יא
וְהַמְשַׂחֵק בְּקֻבִּיָּא עִם הָעַכּוּ''ם אֵין בּוֹ אִסּוּר גֵּזֶל אֲבָל יֵשׁ בּוֹ אִסּוּר עוֹסֵק בִּדְבָרִים בְּטֵלִים שֶׁאֵין רָאוּי לְאָדָם שֶׁיַּעֲסֹק כָּל יָמָיו אֶלָּא בְּדִבְרֵי חָכְמָה וּבְיִשּׁוּבוֹ שֶׁל עוֹלָם:
כסף משנה
11.
When a person plays dice with gentiles, he does not violate the prohibition against robbery. He does, however, violate the prohibition against occupying oneself with empty matters. It is not fitting for a person to spend any of his days occupied in anything other than words of wisdom or pursuits that lead to a stable world.

הלכה יב
מְצוּדוֹת חַיָּה וְעוֹפוֹת וְדָגִים שֶׁנָּפְלוּ מִינֵי הַחַיָּה לְתוֹךְ הַמְּצוּדָה וּבָא אַחֵר וּנְטָלָן הֲרֵי זֶה גֵּזֶל מִדִּבְרֵיהֶם מִפְּנֵי שֶׁעֲדַיִן לֹא הִגִּיעוּ לְיַד הַזּוֹכֶה בָּהֶן:
כסף משנה
12.
The following principle applies with regard to snares for beasts, fowl and fish: If an animal falls into such a snare and another person takes it, this is considered robbery by Rabbinic law. It is not considered to be robbery by Scriptural law because they have not as yet entered the possession of the person who acquires them.

הלכה יג
נָהָר הַמּוֹשֵׁךְ וּמַעְיָנוֹת הַנּוֹבְעִין הֲרֵי הֵן שֶׁל כָּל אָדָם. עָנִי הַמְנַקֵּף בְּרֹאשׁ הַזַּיִת זֵיתִים שֶׁל שִׁכְחָה וּבָא עָנִי אַחֵר וּנְטָלָן מֵעַל הָאָרֶץ הֲרֵי זֶה גֵּזֶל מִדִּבְרֵיהֶם. וְאִם הָיָה הֶעָנִי מְקַבֵּץ בְּיָדוֹ בְּרֹאשׁ הַזַּיִת וּמַשְׁלִיךְ לָאָרֶץ הֲרֵי זֶה גֵּזֶל גָּמוּר שֶׁהֲרֵי הִגִּיעוּ לְיַד הַזּוֹכֶה בָּהֶן:
כסף משנה
13.
A river and a stream that flow belong to all people.
When a poor person climbs to the top of an olive tree and beats the branches so that olives that have been forgotten by their owner will fall, he is entitled to them. If another poor person takes them, it is considered robbery by Rabbinic decree.
If the poor person collects them in his hand and then throws them to the earth, taking them is full-fledged robbery, for they have entered the possession of the person who acquires them.

הלכה יד
הַדְּבוֹרִים אֵינָן בִּרְשׁוּתוֹ שֶׁל אָדָם כְּמוֹ תַּרְנְגוֹלִים וַאֲוָזִים וְאַף עַל פִּי כֵן יֵשׁ בָּהֶן קִנְיָן מִדִּבְרֵיהֶם. וְהַגּוֹזֵל נְחִיל דְּבוֹרִים אוֹ שֶׁמְּנָעוֹ מִבְּעָלָיו אִם בָּא לִרְשׁוּתוֹ הֲרֵי זֶה גֵּזֶל מִדִּבְרֵיהֶם. לְפִיכָךְ מִי שֶׁיָּצָא נְחִיל שֶׁל דְּבוֹרִים מֵרְשׁוּתוֹ וְשָׁכַן בִּרְשׁוּת חֲבֵרוֹ יֵשׁ לְבַעַל הַנְּחִיל לְהַלֵּךְ בְּתוֹךְ שְׂדֵה חֲבֵרוֹ עַד שֶׁיִּטּל אֶת נְחִילוֹ. וְאִם הִזִּיק מְשַׁלֵּם מַה שֶּׁהִזִּיק. אֲבָל לֹא יָקֹץ אֶת שׂוֹכֹה עַל מְנָת לִתֵּן דָּמִים:
כסף משנה
14.
Unlike chickens and ducks, bees are not considered the private property of a person according to Scriptural law. Nevertheless, it is possible to acquire them according to Rabbinic law.
A person who steals a swarm of bees or prevents their owner from taking them if the swarm comes into his domain is considered a robber by Rabbinic decree. Thus, if a swarm of bees leaves a person's property and comes to rest in a colleague's property, the owner of the bees has the right to enter his colleague's field and proceed until he takes his bees. If in his progress he damages his colleague's field, he must reimburse him for the damages. He may not, however, cut down a branch with the intent that later he will reimburse the owner for the damages.

הלכה טו
נֶאֱמֶנֶת אִשָּׁה אוֹ קָטָן לוֹמַר מִכָּאן יָצָא נְחִיל זֶה וְהוּא שֶׁיִּהְיוּ מְשִׂיחִין לְפִי תֻּמָּן וְיִהְיוּ הַבְּעָלִים מְרַדְּפִין אַחַר הַנְּחִיל וְשׁוֹאֲלִים הֵיכָן חוֹנֶה. וְאַף עַל פִּי שֶׁאֵין אִשָּׁה אוֹ קָטָן בְּנֵי עֵדוּת הוֹאִיל וְקִנְיַן דְּבוֹרִים מִדִּבְרֵיהֶם הֶאֱמִינוּ אוֹתָם בּוֹ:
כסף משנה
15.
We accept the statements of a woman or a minor who says, "this swarm of bees left this property," provided that the statements are made in the course of conversation and the owners are pursuing the swarm and asking "Where did it come to rest?"
Although a woman or a minor is not generally accepted as a witness, since the ownership of bees is a matter of Rabbinic law, their testimony is accepted in this case.

הלכה טז
כָּל מִי שֶׁיֵּשׁ בְּיָדוֹ גֵּזֶל שֶׁל דִּבְרֵיהֶם אֵינוֹ יוֹצֵא מִיָּדוֹ בְּדַיָּנִין. וְכֵן אִם כָּפַר בּוֹ וְנִשְׁבַּע אֵינוֹ מוֹסִיף חֹמֶשׁ כְּמוֹ שֶׁמּוֹסִיף עַל הַגֵּזֶל הַגָּמוּר:
כסף משנה
16.
Whenever a person is in possession of property that is considered to be robbed according to Rabbinic law, it cannot be expropriated by judges.
Similarly, if the person denied possession of it and took a false oath to that effect, he is not required to add a fifth, as he is with regard to property acquired by full-fledged robbery.

נזיקין הלכות גזילה ואבידה פרק ו
Nezikim Gezeilah and Aveidah Chapter 6