Bava Metzia 69B

כהאי גונא ודאי צריך לאודועיה: זוזי, מי שקיל טבי ושביק חסרי?

In a case like this it is certainly necessary to inform the litigant of the reasons for the decision. Although a judge is not always obligated to explain the reasons for his decision to the litigants, in a case like this, where there is room for suspicion, he must. Rav Pappa explained: Last year, when the other individual divided money, did he take the good coins and leave the deficient ones?

אמר ליה: לא. אמר ליה: חמרא, כולי עלמא ידעי דאיכא דבסים ואיכא דלא בסים.

The Samaritan said to him: No, he simply divided the money without any particular consideration, and that was acceptable, as there is no difference between one coin and another. Rav Pappa said to him: With regard to wine, everyone knows that there is wine that is sweet and there is wine that is not sweet, so it is not equitable to simply divide the jugs evenly. Therefore, I ruled that you were not entitled to divide the wine without your partner’s knowledge.

גופא, אמר רב נחמן: זוזי, כמאן דפליגי דמו. הני מילי טבי וטבי, תקולי ותקולי. אבל טבי ותקולי ⁠– לא.

The Talmud now returns to discuss the matter itself: Rav Naḥman said: Money is considered as if it were already divided and there is no need to actually divide it in the presence of both of them. The Talmud comments: This matter applies when he divided between good dinars and good dinars, or heavy dinars and heavy dinars, as then there is no need for evaluation. But if some of the coins were good and some were heavy, it is not permitted for him to divide them without informing the other party, as either one may have a preference for a particular type of coin.