Bava Kamma 45B

דאמר: שוכר כשומר חנם דמי, ליתני: חוץ משומר חנם והשוכר!

who says that a renter is considered like an unpaid bailee with regard to his responsibility for the rented item, let it teach that bailees are liable to compensate the owner, with the exception of an unpaid bailee and a renter.

ואי כרבי יהודה, דאמר: שוכר כנושא שכר דמי ⁠– ניתני: ״חוץ משומר חנם, וכולן במועדין פטורין לענין כופר״!

And if it is in accordance with the opinion of R' Yehuda, who says that a renter is considered like a paid bailee, let it teach: With the exception of an unpaid bailee, as it in fact states; but it should also state that in a case where the oxen are forewarned, all of them are exempt with regard to ransom, as R' Yehuda says in the next Mishnah that a forewarned ox requires only a reduced level of safeguarding. Therefore, this baraita does not appear to be in accordance with the opinion of either tanna.

אמר רב הונא בר חיננא: הא מני ⁠– רבי אליעזר היא, דאמר: אין לו שמירה אלא סכין; ולענין שוכר סבר לה כרבי יהודה, דאמר: שוכר כנושא שכר דמי.

Rav Huna bar Ḥinnana said: In accordance with whose opinion is this baraita? It is in accordance with the opinion of R' Eliezer, who says that an ox has no sufficient safeguarding at all other than slaughtering it with a knife; i.e., there is no degree of safeguarding that exempts the ox’s owner, or in the context of the baraita, the bailee, from liability if the ox causes damage or kills. And with regard to a renter, the baraita holds in accordance with the opinion of R' Yehuda, who says that a renter is considered like a paid bailee.

אביי אמר: לעולם כרבי מאיר ⁠– וכדמחליף רבה בר אבוה, ותני: שוכר כיצד משלם? רבי מאיר אומר: כשומר שכר, רבי יהודה אומר: כשומר חנם.

Abaye said: Actually, the baraita is in accordance with the opinion of R' Meir; and it is as Rabba bar Avuh reversed the two opinions and taught: How does a renter pay? In other words, what is his degree of responsibility? R' Meir says: Like a paid bailee. R' Yehuda says: Like an unpaid bailee.