Kiddushin 43B

וכן בדיני ממונות.

And a similar halakha applies with regard to cases of monetary law. If one appoints agents to perform a transaction for him, e.g., paying a debt to his creditor, they can testify that he has paid.

וצריכא דאי אשמעינן בקידושין ⁠– משום דלמיסרה קאתי, אבל גירושין ⁠– ניחוש שמא עיניו נתן בה.

The Talmud comments: And it is necessary for Rav Naḥman to teach this halakha in each of these legal domains, as had he taught us this halakha only in the case of betrothal one could say that the agents can serve as witnesses because they are coming to render her forbidden to everyone else, and therefore there is no reason to suspect them of lying, as their testimony renders her forbidden to them as well. But with regard to divorce, we should be concerned that perhaps the agent cast his eyes upon her and is testifying falsely so that he can marry her.

ואי אשמעינן גירושין ⁠– משום דאיתתא לבי תרי לא חזיא, אבל ממונא ⁠– אימא: הני מיפלג פלגי. צריכי.

And had Rav Naḥman taught us this halakha only in the case of divorce, it could have been said that the agents are not suspected of lying because a woman is not fit for marrying two people, and since they testify as a pair there is no concern that they both might have designs upon her. But with regard to money, one might say that these two can divide it between them, and perhaps they never paid the debt but kept the money themselves. Therefore, all the examples are necessary.

מאי קסבר? אי קסבר המלוה חבירו בעדים צריך לפורעו בעדים ⁠– הני נוגעים בעדות נינהו, דאי אמרי: ״לא פרעניה״ אמר להו: ״פרעוני״!

The Talmud asks: What does Rav Naḥman hold? If he holds that in the case of one who lends money to another in the presence of witnesses, the debtor must repay him in the presence of witnesses, then these agents are affected by their testimony. As, if they say: We did not repay him but returned the money to the one who appointed us, then the one who appointed them will say to them: Pay me back the money I gave you to repay the debt. The agents are considered as the debtors of the one who appointed them, as they took money from him. They would not be deemed credible to state that they returned the money to the one who appointed them, as they do not have witnesses that they did so. Consequently, they have a financial incentive to testify falsely that they fulfilled their agency and repaid the debt.