Halacha

הלכה א
אַרְבָּעָה שׁוֹמְרִים נֶאֶמְרוּ בַּתּוֹרָה וּשְׁלֹשָׁה דִּינִין יֵשׁ לָהֶם. וְאֵלּוּ הֵן הָאַרְבָּעָה שׁוֹמְרִין. שׁוֹמֵר חִנָּם. וְהַשּׁוֹאֵל. וְנוֹשֵׂא שָׂכָר. וְהַשּׂוֹכֵר:
כסף משנה
1.
The Torah mentions four types of watchmen, who are governed by three different rules. The four types of watchmen are an unpaid watchman, a borrower, a paid watchman and a renter.

הלכה ב
וְאֵלּוּ הֵן שְׁלֹשָׁה דִּינִין שֶׁלָּהֶן. שׁוֹמֵר חִנָּם שֶׁנִּגְנַב הַפִּקָּדוֹן מִמֶּנּוּ אוֹ אָבַד וְאֵין צָרִיךְ לוֹמַר אִם נֶאֱנַס הַפִּקָּדוֹן אֹנֶס גָּדוֹל כְּגוֹן שֶׁהָיְתָה בְּהֵמָה וּמֵתָה אוֹ נִשְׁבֵּית הֲרֵי זֶה נִשְׁבָּע שֶׁשָּׁמַר כְּדֶרֶךְ הַשּׁוֹמְרִין וּפָטוּר שֶׁנֶּאֱמַר (שמות כב ו) "וְגֻנַּב מִבֵּית הָאִישׁ" וְגוֹ' (שמות כב ז) "וְנִקְרַב בַּעַל הַבַּיִת אֶל הָאֱלֹהִים". הַשּׁוֹאֵל מְשַׁלֵּם הַכּל בֵּין שֶׁאָבַד דָּבָר הַשָּׁאוּל אוֹ נִגְנַב בֵּין שֶׁאֵרְעוֹ אֹנֶס גָּדוֹל מִזֶּה כְּגוֹן שֶׁמֵּתָה הַבְּהֵמָה הַשְּׁאוּלָה אוֹ נִשְׁבְּרָה אוֹ נִשְׁבֵּית שֶׁכָּךְ כָּתוּב בְּשׁוֹאֵל (שמות כב יג) "וְנִשְׁבַּר אוֹ מֵת בְּעָלָיו אֵין עִמּוֹ שַׁלֵּם יְשַׁלֵּם". נוֹשֵׂא שָׂכָר אוֹ הַשּׂוֹכֵר שְׁנֵיהֶם דִּין אֶחָד יֵשׁ לָהֶן אִם נִגְנַב אוֹ אָבַד הַדָּבָר הַשָּׂכוּר אוֹ שֶׁנָּטַל שָׂכָר עַל שְׁמִירָתוֹ הֲרֵי אֵלּוּ מְשַׁלְּמִים. וְאִם אֵרְעוֹ אֹנֶס גָּדוֹל מִזֶּה כְּגוֹן שֶׁהָיְתָה בְּהֵמָה וּמֵתָה אוֹ נִשְׁבְּרָה אוֹ נִשְׁבֵּית אוֹ נִטְרְפָה הֲרֵי אֵלּוּ נִשְׁבָּעִין שֶׁנֶּאֶנְסָה וּפְטוּרִין שֶׁנֶּאֱמַר (שמות כב ט) "וּמֵת אוֹ נִשְׁבַּר אוֹ נִשְׁבָּה אֵין רֹאֶה" (שמות כב י) "שְׁבֻעַת ה'" וְגוֹ' וּכְתִיב (שמות כב יא) "אִם גָּנֹב יִגָּנֵב מֵעִמּוֹ יְשַׁלֵּם לִבְעָלָיו" וְגוֹ'. נִמְצֵאתָ אוֹמֵר שׁוֹמֵר חִנָּם נִשְׁבָּע עַל הַכּל. וְהַשּׁוֹאֵל מְשַׁלֵּם אֶת הַכּל חוּץ מִן הַמֵּתָה בִּשְׁעַת מְלָאכָה כְּמוֹ שֶׁיִּתְבָּאֵר. נוֹשֵׂא שָׂכָר וְהַשּׂוֹכֵר מְשַׁלְּמִין אֶת הָאֲבֵדָה וְאֶת הַגְּנֵבָה וְנִשְׁבָּעִין עַל הָאֳנָסִין הַגְּדוֹלִים כְּגוֹן שְׁבוּרָה וּשְׁבוּיָה וּמֵתָה וּטְרֵפָה. אוֹ שֶׁאָבַד הַדָּבָר בִּסְפִינָה שֶׁטָּבְעָה בַּיָּם אוֹ נִלְקַח בְּלִסְטִים מְזֻיָּן וְכָל כַּיּוֹצֵא בְּאֵלּוּ מִשְּׁאָר אֳנָסִין הַגְּדוֹלִים:
כסף משנה
2.
These are the three rules that govern cases involving these watchmen: When an entrusted article is stolen from or lost by an unpaid watchman and - needless to say, when the entrusted article is destroyed by forces beyond the watchman's control - e.g., it was an animal and it died or was taken captive -the watchman must take an oath that he guarded the article in a manner appropriate for a watchman, and then he is freed of liability, as Exodus 22:6-7 states: "And it was stolen from the man's home... and the homeowner shall approach the judges."
A borrower must make restitution in all instances, whether the borrowed object was lost, stolen, or destroyed by factors beyond his control - e.g., a borrowed animal died, was injured or taken captive. For with regard to a borrower, ibid.:13 states: "If it becomes injured or dies - when its owner is not with it - he must certainly make restitution."
A paid watchman and a renter are governed by the same laws. If the article that was rented or was entrusted for a fee was lost or stolen, they must make restitution. If the article is lost by forces beyond the watchman's control - e.g., an animal died, was injured, was taken captive or was attacked by a wild animal - the watchman is required to take an oath, and then he is freed of liability, as ibid.:9-10 states: "If it died, was injured or taken captive, and there are no witnesses, an oath of God shall be between them." And ibid.:11 states: "If it is stolen from him, he shall make restitution to its owner."
Thus, an unpaid watchman takes an oath in all instances. A borrower makes restitution in all instances except when an animal dies performing the labor for which it was borrowed, as will be explained. And a paid watchman and a renter make restitution when the article is lost or stolen, and take an oath when it is destroyed by forces beyond their control - e.g., it was injured, taken captive, died, attacked by beasts, lost in a ship that sank at sea, seized by armed thieves - or lost in any other major matter over which the watchman has no control.

הלכה ג
הַמַּפְקִיד אֵצֶל חֲבֵרוֹ בֵּין בְּחִנָּם בֵּין בְּשָׂכָר אוֹ הִשְׁאִילוֹ אוֹ הִשְׂכִּירוֹ אִם שָׁאַל הַשּׁוֹמֵר אֶת הַבְּעָלִים עִם הַדָּבָר שֶׁלָּהֶן אוֹ שְׂכָרָן הֲרֵי הַשּׁוֹמֵר פָּטוּר מִכְּלוּם. אֲפִלּוּ פָּשַׁע בַּדָּבָר שֶׁשָּׁמַר וְאָבַד מֵחֲמַת הַפְּשִׁיעָה הֲרֵי זֶה פָּטוּר שֶׁנֶּאֱמַר (שמות כב יד) "אִם בְּעָלָיו עִמּוֹ לֹא יְשַׁלֵּם אִם שָׂכִיר הוּא בָּא בִּשְׂכָרוֹ". בַּמֶּה דְּבָרִים אֲמוּרִים כְּשֶׁשָּׁאַל הַבְּעָלִים אוֹ שְׂכָרָן בְּעֵת שֶׁנָּטַל הַחֵפֶץ אַף עַל פִּי שֶׁאֵין הַבְּעָלִים שָׁם עִמּוֹ בְּעֵת הַגְּנֵבָה וְהָאֲבֵדָה אוֹ בְּעֵת שֶׁנֶּאֱנַס. אֲבָל נָטַל הַחֵפֶץ וְנַעֲשָׂה עָלָיו שׁוֹמֵר תְּחִלָּה וְאַחַר כָּךְ שָׂכַר הַבְּעָלִים אוֹ שְׁאָלָן אַף עַל פִּי שֶׁהָיוּ הַבְּעָלִים עוֹמְדִין שָׁם בְּעֵת שֶׁנֶּאֱנַס הַדָּבָר הַשָּׁמוּר הֲרֵי זֶה מְשַׁלֵּם שֶׁנֶּאֱמַר (שמות כב יג) "בְּעָלָיו אֵין עִמּוֹ שַׁלֵּם יְשַׁלֵּם" מִפִּי הַשְּׁמוּעָה לָמְדוּ הָיָה עִמּוֹ בִּשְׁעַת הַשְׁאָלָה אַף עַל פִּי שֶׁאֵינוֹ בְּעֵת הַגְּנֵבָה וְהַמִּיתָה פָּטוּר לֹא הָיָה עִמּוֹ בִּשְׁעַת הַשְׁאָלָה אַף עַל פִּי שֶׁהָיָה עִמּוֹ בְּעֵת הַמִּיתָה אוֹ הַשְּׁבִיָּה חַיָּב. וְהוּא הַדִּין לִשְׁאָר הַשּׁוֹמְרִים שֶׁכֻּלָּן בִּבְעָלִים פְּטוּרִין אֲפִלּוּ פְּשִׁיעָה בִּבְעָלִים פָּטוּר:
כסף משנה
3.
The following rules apply when a person entrusts an article to a colleague for safekeeping, whether he offers payment or not or lends an article or hires it out. If the watchman also asks the owner of the article to work for him or hires him together with the article, the watchman is never held liable at all. Even if the watchman is negligent in his care of the article he was watching, and it was lost because of his negligence, he is not liable, as Exodus 22:14 states: "If his owner is with him, he need not make restitution. If he is a hired worker, it comes with his wages."
When does the above apply? When the watchman asked or hired the owner to work at the time he took the article, even if the owner was not with him at the time the article was stolen, lost or destroyed by forces beyond his control. If, by contrast, he took the article and became responsible as a watchman at the outset, and afterwards asked or hired the owner to work, he is not absolved of responsibility. Even if the owner was standing nearby at the time the entrusted article was destroyed by forces beyond the watchman's control, the watchman is liable to pay, as implied by ibid.: 13: "If the owner is not with him, he must certainly make restitution."
According to the Oral Tradition, these verses were interpreted to mean: If the owner was with the borrower at the time the article or animal was borrowed, he is not liable, even if he was not with him at the time it was stolen or died. If, however, he was not with the borrower at the time the article or animal was borrowed, he is liable, even if he was with him at the time it was stolen or died. The same laws apply to other watchmen. If the owners are "with them", they are all free of liability. Even if they are negligent, if the owners are "with them", they are all free of liability.

הלכה ד
כָּל שׁוֹמֵר שֶׁפָּשַׁע בִּתְחִלָּתוֹ אַף עַל פִּי שֶׁנֶּאֱנַס בְּסוֹפוֹ חַיָּב כְּמוֹ שֶׁיִּתְבָּאֵר. וְאֵין הַשּׁוֹאֵל רַשַּׁאי לְהַשְׁאִיל אֲפִלּוּ שָׁאַל סֵפֶר תּוֹרָה שֶׁכָּל שֶׁקּוֹרֵא בּוֹ עוֹשֶׂה מִצְוָה לֹא יַשְׁאִילֶנּוּ לְאַחֵר. וְכֵן אֵין הַשּׂוֹכֵר רַשַּׁאי לְהַשְׂכִּיר אֲפִלּוּ הִשְׂכִּירוֹ סֵפֶר תּוֹרָה לֹא יַשְׂכִּירֶנּוּ לְאַחֵר שֶׁהֲרֵי זֶה אוֹמֵר לוֹ אֵין רְצוֹנִי שֶׁיִּהְיֶה פִּקְדוֹנִי בְּיַד אַחֵר. עָבַר הַשּׁוֹמֵר וּמָסַר לַשּׁוֹמֵר הַשֵּׁנִי אִם יֵשׁ עֵדִים שֶׁשְּׁמָרָהּ הַשּׁוֹמֵר הַשֵּׁנִי כְּדֶרֶךְ הַשּׁוֹמְרִין וְנֶאֱנַס פָּטוּר הַשּׁוֹמֵר הָרִאשׁוֹן שֶׁהֲרֵי יֵשׁ עֵדִים שֶׁנֶּאֱנַס. וְאִם אֵין שָׁם עֵדִים חַיָּב הַשּׁוֹמֵר הָרִאשׁוֹן לְשַׁלֵּם לַבְּעָלִים מִפְּנֵי שֶׁמָּסַר לְשׁוֹמֵר אַחֵר וְיַעֲשֶׂה הוּא דִּין עִם הַשּׁוֹמֵר הַשֵּׁנִי. אֲפִלּוּ הָיָה הָרִאשׁוֹן שׁוֹמֵר חִנָּם וּמָסַר לְשׁוֹמֵר שָׂכָר חַיָּב שֶׁהֲרֵי יֵשׁ לְבַעַל הַחֵפֶץ לוֹמַר לוֹ אַתָּה נֶאֱמָן אֶצְלִי לְהִשָּׁבַע וְזֶה אֵינוֹ נֶאֱמָן. לְפִיכָךְ אִם הָיָה דֶּרֶךְ הַבְּעָלִים לְהַפְקִיד תָּמִיד דָּבָר זֶה אֵצֶל הַשּׁוֹמֵר הַשֵּׁנִי הֲרֵי זֶה הַשּׁוֹמֵר הָרִאשׁוֹן פָּטוּר מִלְּשַׁלֵּם שֶׁהֲרֵי הוּא אוֹמֵר לַבְּעָלִים זֶה הַדָּבָר שֶׁהִפְקַדְתֶּם אֶצְלִי אוֹ הִשְׁאַלְתֶּם אֶמֶשׁ הֱיִיתֶם מַפְקִידִין אוֹתוֹ אֵצֶל זֶה שֶׁהִפְקַדְתִּי אֲנִי אֶצְלוֹ. וְהוּא שֶׁלֹּא יְמַעֵט שְׁמִירָתוֹ. כֵּיצַד יְמַעֵט שְׁמִירָתוֹ. כְּגוֹן שֶׁהָיָה מֻפְקָד אֶצְלוֹ בְּשָׂכָר וְהִפְקִידוֹ אֵצֶל אוֹתוֹ הַשֵּׁנִי בְּחִנָּם אוֹ שֶׁהָיָה שָׁאוּל אֶצְלוֹ וְהִפְקִידוֹ אֵצֶל אוֹתוֹ הַשֵּׁנִי בְּשָׂכָר הוֹאִיל וּמִעֵט שְׁמִירָתוֹ פּוֹשֵׁעַ הוּא וּמְשַׁלֵּם. אַף עַל פִּי שֶׁשָּׁאַל אוֹ שֶׁשָּׂכַר בַּבְּעָלִים הֲרֵי הוּא הוֹצִיא הַדָּבָר הַשָּׁמוּר מִיָּדוֹ לְיַד שׁוֹמֵר אַחֵר:
כסף משנה
4.
Whenever a watchman is negligent when he begins caring for the article, even though the article is ultimately destroyed by forces beyond his control, he is liable, as will be explained.
A borrower is not allowed to lend the entrusted article to another person. Even if he borrows a Torah scroll - in which instance, anyone who reads it performs a mitzvah - he may not lend it to someone else. Similarly, a renter is not permitted to rent the entrusted article to another person. Even if a Torah scroll was rented to him, he may not rent it to someone else. The rationale is that the owner will tell the watchman: "I do not want my article to be in someone else's hands."
The following rules apply if the watchman transgressed and entrusted the article to another watchman. If there are witnesses who testify that the second watchman guarded the article in an appropriate manner, and the article was destroyed by forces beyond his control, the first watchman is not liable. For there are witnesses that the article was destroyed by forces beyond his control.
If there are no witnesses to give such testimony, the first watchman is liable to pay the owners, for he entrusted the article to another watchman. Afterwards, he should enter into litigation with the second watchman. Even if the first watchman was not paid for his services and he entrusted the article to a paid watchman, he is liable. For the owner of the article will tell him: "Although you are an unpaid watchman, you are trustworthy in my eyes, and I am willing to believe your oath. I don't consider the other person trustworthy."
For this reason, if the owner of the article would frequently entrust articles of this nature to the second watchman, the first watchman is not required to make restitution. For he could tell the owner: "Yesterday, you were willing to entrust the article that you entrusted to me to this person."
In the above instance, the watchman is freed of liability only when he does not reduce the level of responsibility for watching the article. What is meant by reducing the level of responsibility for watching the article? For example, the article was entrusted to the first watchman for a fee, and he entrusted it to the second watchman without charge, or the first watchman was a borrower, and he entrusted it to a paid watchman. In such instances, since the watchman reduced the level of responsibility for watching the article, he is considered to be negligent and is required to pay.
[The above applies] even if when the article was originally entrusted, the owner was working for or hired by the first watchman. For that watchman removed the entrusted article from his domain and entrusted it to another watchman.

הלכה ה
וְאִם הֵבִיא הַשּׁוֹמֵר הַשֵּׁנִי הָרְאָיָה שֶׁיִּפָּטֵר בָּהּ שׁוֹמֵר רִאשׁוֹן כְּדִין שְׁמִירָתוֹ הֲרֵי זֶה פָּטוּר. כֵּיצַד. שׁוֹמֵר שָׂכָר שֶׁנָּתַן הַבְּהֵמָה הַשְּׁמוּרָה אֶצְלוֹ לְשׁוֹמֵר חִנָּם אִם הֵבִיא הַשּׁוֹמֵר הַשֵּׁנִי עֵדִים שֶׁמֵּתָה הַבְּהֵמָה כְּדַרְכָּהּ הֲרֵי הַשּׁוֹמֵר הָרִאשׁוֹן פָּטוּר. וְכֵן כָּל כַּיּוֹצֵא בָּזֶה:
כסף משנה
5.
If the second watchman was able to bring proof that would free the first watchman from responsibility for guarding the article, he is not liable.
What is implied? A paid watchman entrusted an animal that was entrusted to him to an unpaid watchman. If the second watchman brought witnesses who testify that the animal died in a natural manner, the first watchman is not liable. The same principles apply in all analogous situations.

הלכה ו
שׁוֹמֵר שֶׁמָּסַר לְשׁוֹמֵר אַחֵר וְהוֹסִיף בִּשְׁמִירָתוֹ וּמֵתָה הַהֲנָאָה לַבְּעָלִים. כֵּיצַד. הַשּׂוֹכֵר פָּרָה מֵחֲבֵרוֹ וְהִשְׁאִילָהּ לְאַחֵר וּמֵתָה כְּדַרְכָּהּ בְּיַד הַשּׁוֹאֵל הוֹאִיל וְהַשּׁוֹאֵל חַיָּב בַּכּל יַחְזִירוּ דְּמֵי הַפָּרָה לַבְּעָלִים שֶׁאֵין זֶה הַשּׂוֹכֵר עוֹשֶׂה סְחוֹרָה בְּפָרָתוֹ שֶׁל חֲבֵרוֹ. וְכֵן כָּל כַּיּוֹצֵא בָּזֶה. הָיָה בְּיָדוֹ פִּקָּדוֹן וּשְׁלָחוֹ בְּיַד אַחֵר לִבְעָלָיו הוֹאִיל וְהַשּׁוֹמֵר הָרִאשׁוֹן חַיָּב בְּאַחֲרָיוּתוֹ עַד שֶׁיַּגִּיעַ לְיַד הַבְּעָלִים אִם בָּא לַחְזֹר וּלְהַחְזִיר הַפִּקָּדוֹן מִיַּד הַשּׁוֹמֵר הַשֵּׁנִי מַחְזִיר. וְאִם הֻחְזַק הַשּׁוֹמֵר הָרִאשׁוֹן כַּפְרָן אֵינוֹ יָכוֹל לְהַחְזִיר הַפִּקָּדוֹן מִיַּד הַשּׁוֹמֵר הַשֵּׁנִי אַף עַל פִּי שֶׁעֲדַיִן הַפִּקָּדוֹן בְּאַחֲרָיוּתוֹ שֶׁל רִאשׁוֹן:
כסף משנה
6.
When a watchman entrusted an animal entrusted to him to another watchman and increased the responsibility of the watchman and the animal died, the owner receives the benefit.
What is implied? A person rents a cow from a colleague and then lends it to another person. Afterwards, the cow dies in an ordinary manner in the possession of the borrower. Since the borrower is required to make full restitution, he should return the worth of the cow to its owners. For the renter is not carrying out business with his colleague's cow. Similar principles apply in all analogous situations.
The following rules apply when a person was in possession of an entrusted object belonging to a colleague and gave it to another person to bring to its owner. Since the first watchman is responsible for the article until it reaches its owner's domain, if he desires to retrieve the article from the second watchman, he may. If it is established that the first watchman has denied that property was entrusted to him, he cannot retrieve the article from the second watchman although he remains responsible for the entrusted article.

משפטים הלכות שכירות פרק א
Mishpatim Schirus Chapter 1