Halacha

הלכה א
בְּהֵמָה אוֹ חַיָּה שֶׁאֵינָהּ שְׁמוּרָה אֶלָּא מְהַלֶּכֶת בְּכָל מָקוֹם וְרוֹעָה. אֵינָהּ בְּחֶזְקַת זֶה שֶׁתְּפָסָהּ מֵאַחַר שֶׁהִיא יְדוּעָה לַבְּעָלִים. כֵּיצַד. הֵבִיא הַתּוֹבֵעַ עֵדִים שֶׁהַבְּהֵמָה הַזֹּאת יְדוּעָה לוֹ וְזֶה הַתּוֹפֵס טוֹעֵן אַתָּה נְתַתָּהּ לִי אַתָּה מְכַרְתָּהּ לִי אֵינוֹ נֶאֱמָן. שֶׁאֵין הֱיוֹתָהּ תַּחַת יָדוֹ רְאָיָה שֶׁהֲרֵי הִיא הָלְכָה מֵעַצְמָהּ וְנִכְנְסָה בִּרְשׁוּתוֹ. לְפִיכָךְ אִם לֹא הֵבִיא רְאָיָה תַּחְזֹר הַבְּהֵמָה לִבְעָלֶיהָ וְיִשָּׁבַע הֶסֵּת עַל טַעֲנָה זוֹ:
כסף משנה
1.
We do not presume that an animal or a beast that is not kept in an enclosed place, but instead roams freely and pastures everywhere, belongs to the person who seizes it if the animal is known to have a prior owner.
What is implied? When a plaintiff brings witnesses who testify that a certain animal is known to belong to him, and the person maintaining possession of the animal claims: "You gave it to me" or "You sold it to me," the defendant's word is not accepted. The fact that the animal is in his possession is not considered proof of ownership, because it is possible that it roamed and entered his domain by itself. Therefore, if the defendant does not bring proof of his acquisition of the animal, it should be returned to its owner. The owner must, however, reinforce his claim by taking an oath.

הלכה ב
הָיְתָה הַבְּהֵמָה שְׁמוּרָה אוֹ מְסוּרָה לְרוֹעֶה אַף עַל פִּי שֶׁהֵבִיא זֶה עֵדִים שֶׁהִיא שֶׁלּוֹ הֲרֵי הִיא בְּחֶזְקַת זֶה שֶׁהִיא תַּחַת יָדוֹ וְאִם טָעַן אַתָּה מְכַרְתָּהּ אוֹ נְתַתָּהּ לִי יִשָּׁבַע הַתּוֹפֵס הֶסֵּת שֶׁהִיא שֶׁלּוֹ וְיִפָּטֵר:
כסף משנה
2.
If it was usual for an animal to be kept in an enclosed place or entrusted to a shepherd, we assume that it belongs to the person in whose possession it is found. This applies even if the plaintiff brings witnesses who testify that it belonged to him. Thus, if the person who holds the animal in his possession claims: "You sold it to me" or "You gave it to me," he is required to take a sh'vu'at hesset that it belongs to him, and then he is released of all obligations.

הלכה ג
לְפִיכָךְ מִי שֶׁתָּפַס בֶּהֱמַת חֲבֵרוֹ שֶׁהָיְתָה שְׁמוּרָה אוֹ בְּיַד רוֹעֶה. וְהַבְּעָלִים טוֹעֲנִין הִיא יָצָאת מֵעַצְמָהּ וּבָאָה אֶצְלְךָ אוֹ פִּקָּדוֹן הִיא בְּיָדְךָ אוֹ שְׁאוּלָה הִיא לְךָ. וְהַתּוֹפֵס אוֹמֵר כֵּן הוּא אֵינָהּ שֶׁלִּי אֲבָל אַתָּה חַיָּב לִי כָּךְ וְכָךְ אוֹ אַתָּה מִשְׁכַּנְתָּהּ בְּיָדִי עַל כָּךְ וְכָךְ אוֹ הִזַּקְתָּ אוֹתִי נֵזֶק שֶׁאַתָּה חַיָּב לְשַׁלֵּם כָּךְ וְכָךְ. יָכוֹל לִטְעֹן עַד כְּדֵי דָּמֶיהָ מִתּוֹךְ שֶׁיָּכוֹל לוֹמַר לְקוּחָה הִיא בְּיָדִי וְיִשָּׁבַע בִּנְקִיטַת חֵפֶץ וְיִטּל:
כסף משנה
3.
Therefore, the following rules are applied when a person seizes possession of an animal belonging to a colleague that had been kept in an enclosed place or entrusted to a shepherd. If the owner claims: "The animal went out and came to you on its own initiative," "It was entrusted to you for safekeeping," or "It was lent to you," and the person who seized it agrees, saying: "It is not mine, but you owe me this-and-this much," "You gave it to me as security for this-and-this much," or "You owe me such-and-such for damages that you caused my property," his word is accepted if he claims the value of the animal or less. The rationale is that since he could claim that he purchased it, his word is accepted if he lodges another plausible claim. He must, however, take an oath holding a sacred article. Then he may collect his claim.

הלכה ד
וְכֵן הָעֲבָדִים שֶׁיְּכוֹלִין לְהַלֵּךְ אֵינָן בְּחֶזְקַת זֶה שֶׁהֵן תַּחַת יָדוֹ אֶלָּא כֵּיוָן שֶׁהֵבִיא הַטּוֹעֵן עֵדִים שֶׁזֶּה יָדוּעַ שֶׁהוּא עַבְדּוֹ וְהַלָּה טוֹעֵן אַתָּה מְכַרְתּוֹ לִי אַתָּה נְתַתּוֹ לִי בְּמַתָּנָה אֵינוֹ נֶאֱמָן וְיַחְזֹר הָעֶבֶד לִבְעָלָיו וְיִשָּׁבַע הַטּוֹעֵן שֶׁלֹּא מָכַר וְלֹא נָתַן. הֵבִיא זֶה הַנִּטְעָן שֶׁתָּפַס הָעֶבֶד עֵדִים שֶׁיֵּשׁ לְזֶה הָעֶבֶד אֶצְלוֹ שָׁלֹשׁ שָׁנִים רְצוּפוֹת מִיּוֹם לְיוֹם וְהוּא מִשְׁתַּמֵּשׁ בּוֹ כְּדֶרֶךְ שֶׁהָעֲבָדִים מְשַׁמְּשִׁין אֶת רַבָּן הוֹאִיל וְלֹא מִחָה בּוֹ בְּכָל אֵלּוּ הַשָּׁנִים הֲרֵי זֶה נֶאֱמָן וּמַעֲמִידִין אוֹתוֹ בְּיָדוֹ אַחַר שֶׁיִּשָּׁבַע הֶסֵּת שֶׁלְּקָחוֹ מִמֶּנּוּ אוֹ נְתָנוֹ לוֹ בְּמַתָּנָה. אֲבָל עֶבֶד קָטָן שֶׁאֵינוֹ יָכוֹל לְהַלֵּךְ עַל רַגְלָיו מִפְּנֵי קַטְנוּתוֹ הֲרֵי הוּא כִּשְׁאָר הַמִּטַּלְטְלִין וְכָל מִי שֶׁיִּהְיֶה בִּרְשׁוּתוֹ הֲרֵי הוּא בְּחֶזְקָתוֹ וְהַמּוֹצִיא מֵחֲבֵרוֹ עָלָיו הָרְאָיָה:
כסף משנה
4.
Similar laws apply with regard to servants. Since they can walk independently, the fact that they are in the physical possession of a person is not presumed to be a sign of ownership. Instead, if the plaintiff brings witnesses who testify that it is known that this servant belonged to the plaintiff, the defendant's word is not accepted if he claims: "You sold him to me" or "You gave him to me as a present." Instead, the servant should be returned to its owner. He must, however, take an oath that he did not sell the servant or give him away as a present.
Different rules apply if the defendant who was asserted to have seized possession of the servant brought witnesses who testified that the servant was in his possession, day after day, for three consecutive years, and that the defendant would have him serve him as servants serve their masters. Since the original owner did not raise objections throughout all these years, the defendant's word is accepted. We allow him to maintain possession after he takes a sh'vu'at hesset that he purchased the servant from the original owner or the owner gave the servant to him as a present.
These rules do not apply to a servant who is a young child and cannot walk on his legs because of his youth. He is considered as other types of movable property. We presume that he is owned by the person in whose domain he is located, and we follow the principle: When a person seeks to expropriate property from a colleague, the burden of proof is upon him.

הלכה ה
הַטּוֹעֵן אֶת חֲבֵרוֹ וְאָמַר בֶּגֶד אוֹ בְּהֵמָה אוֹ עֶבֶד זֶה שֶׁבְּיָדְךָ שֶׁלִּי הוּא אוֹ שָׁאוּל אוֹ גָּזוּל אוֹ הִפְקַדְתִּיו אֶצְלְךָ אוֹ שָׂכוּר לְךָ. וְהַנִּטְעָן אָמַר לֹא כִּי אֶלָּא זֶה מָמוֹנִי וִירֻשָּׁתִי. וְהֵבִיא הַטּוֹעֵן עֵדִים שֶׁהֵעִידוּ שֶׁהֵן יוֹדְעִין שֶׁזֶּה הַחֵפֶץ אוֹ הָעֶבֶד אוֹ הַבְּהֵמָה יְדוּעָה שֶׁהִיא הָיְתָה לָזֶה. חָזַר הַנִּטְעָן וְאָמַר כֵּן הָיָה שֶׁלְּךָ אֲבָל אַתָּה נְתַתּוֹ לִי אוֹ מְכַרְתּוֹ לִי וְזֶה שֶׁאָמַרְתִּי יְרֻשָּׁתִי לֹא שֶׁיְּרַשְׁתִּיו מֵאֲבוֹתַי אֶלָּא שֶׁהִיא שֶׁלִּי כְּאִלּוּ יְרַשְׁתִּיו. הֲרֵי זֶה נֶאֱמָן וְנִשְׁבָּע הֶסֵּת. שֶׁכְּבָר בֵּאַרְנוּ שֶׁיֵּשׁ לַטּוֹעֵן לַחְזֹר לִטְעֹן דָּבָר הַנִּשְׁמָע:
כסף משנה
5.
As we explained, a plaintiff can alter his statements and offer another claim if it is plausible. To apply that concept to the issues at hand: A person issued a claim against a colleague, stating: "This garment...", "This animal...", or "This servant that is in your possession belongs to me. It was lent to you," "... it is stolen," "... I entrusted it to you," or "... I rented it to you."
The defendant claimed, "No. It is my money. I inherited it." The plaintiff then brought witnesses who testified that they know that this article, servant, or animal is known to belong to the plaintiff. The defendant then countered and replied: "Yes. It was yours, but you gave it to me..." or "... you sold it to me. I said: 'I inherited it,' not because I inherited it from my father, but that my ownership is so strong that it is as if I inherited it." The defendant's claim is accepted provided that he supports it by taking a sh'vu'at hesset.

הלכה ו
סְפִינָה וְכַיּוֹצֵא בָּהּ שֶׁהָיוּ שְׁנַיִם נֶחְלָקִין עָלֶיהָ זֶה אוֹמֵר כֻּלָּהּ שֶׁלִּי וְזֶה אוֹמֵר כֻּלָּהּ שֶׁלִּי וּבָאוּ לְבֵית דִּין וְאָמַר אֶחָד תִּפְסוּהָ עַד שֶׁאָבִיא עֵדִים אֵין תּוֹפְסִין אוֹתָהּ. וְאִם תְּפָסוּהָ בֵּית דִּין וְהָלַךְ וְלֹא מָצָא עֵדִים וְאָמַר הַנִּיחוּהָ בֵּינֵינוּ וְכָל הַמִּתְגַּבֵּר יִטּל כְּשֶׁהָיָה דִּינָהּ מִקֹּדֶם אֵין שׁוֹמְעִין לָהֶן וְאֵין מוֹצִיאִין אוֹתָהּ בֵּית דִּין מִיָּדָן עַד שֶׁיָּבִיאוּ עֵדִים אוֹ עַד שֶׁיּוֹדוּ זֶה לָזֶה אוֹ יַחֲלֹקוּ בִּרְצוֹנָם וּבִשְׁבוּעָה כְּמוֹ שֶׁבֵּאַרְנוּ:
כסף משנה
6.
The following laws apply when two people are contending with regard to a boat or the like, each claiming: "It belongs entirely to me." If they come to the court and one asks the court: "Take possession of it until I bring witnesses to support my claim," the court should not take possession of it.
If the court took possession of it, that person went and did not find witnesses, and returned and asked: "Leave it for us as before, and whoever will overcome the other will acquire it, as was the law before," it does not heed the request. Instead, the court does not release it from its possession until a claimant brings witnesses who support his claim, one acknowledges the truth of the other's claim, or they willingly agree to divide it after taking an oath, as we have explained.

משפטים הלכות טוען ונטען פרק י
Mishpatim To`en and Nitan Chapter 10