Commentary for Bava Kamma 5:3
הִכְנִיס שׁוֹרוֹ לַחֲצַר בַּעַל הַבַּיִת שֶׁלֹּא בִרְשׁוּת, וּנְגָחוֹ שׁוֹרוֹ שֶׁל בַּעַל הַבַּיִת, אוֹ שֶׁנְּשָׁכוֹ כַלְבּוֹ שֶׁל בַּעַל הַבַּיִת, פָּטוּר. נָגַח הוּא שׁוֹרוֹ שֶׁל בַּעַל הַבַּיִת, חַיָּב. נָפַל לְבוֹרוֹ וְהִבְאִישׁ מֵימָיו, חַיָּב. הָיָה אָבִיו אוֹ בְנוֹ לְתוֹכוֹ, מְשַׁלֵּם אֶת הַכֹּפֶר. וְאִם הִכְנִיס בִּרְשׁוּת, בַּעַל הֶחָצֵר חַיָּב. רַבִּי אוֹמֵר, בְּכֻלָּן אֵינוֹ חַיָּב, עַד שֶׁיְּקַבֵּל עָלָיו לִשְׁמֹר:
If one brought his ox into the courtyard of the ba'al habayith without permission, and the ox of the ba'al habayith gored it or the dog of the ba'al habayith bit it, he is not liable. If it gored the ox of the ba'al habayith, it is liable. If it fell into his pit and fouled his waters, he is liable. If his [the ba'al habayith's] father or mother were in it [(The same applies with others, but the common instance is given)], he pays kofer. [as when it were a muad to throw itself upon people in pits, and that day it saw greens in the pit and threw itself into the pit to eat the greens and killed a man, in which instance the ox is not put to death, since it killed without intent, and the owner pays kofer (Scripture indicating kofer liability even in the absence of intent, as stated above)]. And if he brought it in with permission, the ba'al habayith is liable. Rebbi says: In all of them (the aforementioned instances), he (the ba'al habayith) is not liable unless he takes it upon himself to guard (against damage). [The halachah is in accordance with Rebbi. Therefore, if he brought in his ox with the permission of the ba'al habayith, unqualified, the ba'al habayith not undertaking to guard, he is not liable, not having assumed responsibility. And the one who brings it in, too, is not liable, having brought it in with permission.]
Rambam on Mishnah Bava Kamma
Bartenura on Mishnah Bava Kamma
English Explanation of Mishnah Bava Kamma
Rabbi says: “In no case is [the householder] liable unless he had agreed to watch over it.
The first two clauses of mishnah three are similar to what we learned in the previous mishnah. We again learn that if a person brings his belongings onto another person’s property without permission and they are damaged he will not receive compensation and if they cause damages he is liable. In clause b we learn an additional law. If when falling into the cistern the ox kills a person, the owner of the ox is obligated to pay the ransom price mentioned in Exodus 21:30. As we learned in chapter four mishnah 5 when an ox kills a person, the owner of the ox is obligated to pay a ransom price to the family of the deceased. In our mishnah we learn that falling into a cistern is similar enough to goring that the ox’s owner is obligated.
At the end of this mishnah we learn that Rabbi (Rabbi Judah Hanasi) holds an opinion different from that held in the anonymous previous portions of the mishnah. According to Rabbi, allowing a person to enter one’s property is not tantamount to accepting upon oneself the obligation to watch over that person’s belongings. When I allow you to bring your belongings onto my property, I may still assume that you will watch over your things. Therefore, if they cause damage you are still obligated and if they are damaged I am exempt. According to Rabbi, a person does not accept the responsibility for watching the belongings until he states so explicitly. The other opinion in the mishnah held that by allowing a person to enter one’s property on is implicitly accepting upon himself the responsibility for that person’s belongings.