Responsa for Gittin 127:15
ואמאי וליהימניה לשליש מי קא נפיק גיטא מתותי ידיה דלהימניה
If the husband says [that he gave it to the depository] to divorce with, and the depository says [it was given] to divorce with, and the wife says, He gave it to me but it has been lost, R. Johanan says: This is a statement bearing on forbidden relationships, and a statement bearing on a forbidden relationship must be substantiated by not less than two witnesses. But why so? Why not believe the depository? — Is he able to produce the Get that we should believe him? Then let us believe the husband, in accordance with what R. Hiyya b. Abin said in the name of R. Johanan: If a husband says, I have divorced my wife, his word can be taken? — Does he here say, I have divorced her?<span class="x" onmousemove="('comment',' He appointed an agent to hand it over to her. ');"><sup>13</sup></span>
Teshuvot Maharam
A. A neutral party is believed without an oath. We cannot require an oath of B; for if we do, no one will do a favor for a friend lest he claim to have stipulated conditions for such a favor and the benefactor would be required to take an oath. Therefore, B is free from any obligation to A unless the latter claims that B received the two marks from C, in which case B has to take an oath to the effect that he did not receive anything from C.
SOURCES: Pr. 277.
Teshuvot Maharam
A. A trustee appointed by both parties is not required to take an oath regarding the terms of his trusteeship. But, Leah was not appointed trustee by both parties. She was only appointed by the husband, and, therefore, is required to take an oath. Leah's husband cannot object to imposing an oath on her. If the law requires that a woman take an oath, the husband has no right to protest against her being degraded in court. But, since Leah, as long as she is married, has no money of her own, and were she to claim that she had already returned the deposit, no oath would be imposed on her, we now lend credence to her words and require no oath. However, the court should give A a writ stating that after Leah will be divorced or widowed she will have to return the money to A or take an oath to the effect that A deposited the money with her on condition that she return it upon his wife's consent only.
SOURCES: L. 306–7; Mord. B. K. 89. Cf. Pr. 739; Tesh. Maim. to Mishpatim, 44.