Bava Metzia 38A

והא טעמא דרבי יוסי משום הפסד הרמאי הוא. אלא תרוייהו לרבנן איצטריך, ולא זו אף זו קתני.

The Talmud asks: But isn’t the reason for the opinion of R' Yosei as he stated in the Mishnah: Due to the loss of the fraud? It is not due to the fact that the vessel will not remain intact. Consequently, there is no reason to believe that R' Yosei would concede to the Rabbis in the instance where money was deposited. Rather, both of the cases are necessary according to the Rabbis. And although the first case could have been inferred from the second case, the tanna teaches the Mishnah employing the style of: Not only this but also that, i.e., the Mishnah began with an obvious example and continued with a more novel one.

מתני׳ המפקיד פירות אצל חבירו, אפילו הן אבודין ⁠– לא יגע בהן. רבן שמעון בן גמליאל אומר: מוכרן בפני בית דין, מפני שהוא כמשיב אבידה לבעלים.

Mishnah: In the case of one who deposits produce with another, even if it is lost due to spoilage or vermin, the bailee may not touch it, as it is not his. Rabban Shimon ben Gamliel says: He sells it before the court, as by doing so he is like one returning a lost item to the owner, since through its sale he prevents the owner from losing the value of his produce.

גמ׳ מאי טעמא? אמר רב כהנא: אדם רוצה בקב שלו מתשעה קבים של חבירו. ורב נחמן בר יצחק אמר: חיישינן שמא עשאן המפקיד תרומה ומעשר על מקום אחר.

Talmud: What is the reason that the first tanna said that the bailee should not touch the produce? Rav Kahana says that it is based on the principle: A person prefers a kav of his own produce to 9 kav of another’s produce. Consequently, despite the spoilage, the owner prefers that the bailee not touch the produce. Rav Naḥman bar Yitzḥak says: We are concerned that perhaps the one who deposited the produce rendered it teruma and tithe for produce in another place, resulting in the buyer consuming produce that is teruma and tithe inappropriately.