Responsa for Bava Metzia 163:3
כולה רבי יהודה היא וחסורי מיחסרא והכי קתני הלוהו על המשכון שומר שכר במה דברים אמורים שהלוהו פירות אבל הלוהו מעות שומר חנם שרבי יהודה אומר הלוהו מעות שומר חנם הלוהו פירות שומר שכר
But since the following clause states, R. JUDAH SAID: IF HE LENDS HIM MONEY ON A PLEDGE, HE IS AN UNPAID TRUSTEE; IF PROVISIONS, HE IS A PAID BAILEE; that proves that the first Tanna admits no distinction! — The whole [Mishnah] is according to R. Judah, but it is defective, and should read thus: IF A MAN LENDS ANOTHER ON A PLEDGE, HE RANKS AS A PAID TRUSTEE; this holds good only if he lends him provisions; but if money, he is an unpaid trustee. For R. JUDAH SAID: IF HE LENDS HIM MONEY ON A PLEDGE, HE IS AN UNPAID TRUSTEE; IF PROVISIONS, HE IS A PAID BAILEE. But if so, does not the Mishnah disagree with R. Akiba?<span class="x" onmousemove="('comment',' Since R. Akiba maintains that if the pledge is lost the money too is lost, he treats him as a paid bailee even in the case of money. Whereas it is a general principle that an anonymous Mishnah is R. Meir's, and taught on the basis of R. Akiba's view; V. Sanh. 86a. ');"><sup>3</sup></span>
Teshuvot Maharam
A. Since Ri ruled that the opinion of Rabba prevails, that the responsibility of a keeper of a lost object is that of a gratuitous bailee (B. M. 82a), the responsibility of the creditor toward the excess value of the pledge is also that of a gratuitous bailee. Although some authorities are of the opposite opinion, the very fact that a difference of opinion exists creates a doubt as to the law; and in case of doubt we do not render a verdict to collect.
SOURCES: Am II, 161; Mord. Sheb. 774; Tesh. Maim. to Mishpatim, 56; Agudah Sheb. 36; cf. Pr. 185; ibid. 699b.