Bava Metzia 69A

אי פלגא בהפסד ⁠– תרי תילתי באגר.

or it must have been that the other party accepted one-half of the loss and that Rav Ilish was entitled to 2/3rds of the profit. Either way, the disparity in the terms served as payment to Rav Ilish for his effort, removing any concern about violation of the prohibition of interest.

אמר רב כהנא: אמריתא לשמעתא קמיה דרב זביד מנהרדעא, ואמר לי: דלמא רב עיליש טובל עמו בציר הוה. ואמר רב נחמן: הלכה כרבי יהודה! אמר ליה: לאו הלכתא איתמר, אלא שיטה איתמר.

Rav Kahana said: I said this halakha before Rav Zevid of Neharde’a and he said to me: Why is it certain that the document included all the details of the transaction? Perhaps Rav Ilish immersed his bread in brine together with the other party? According to the opinion of R' Yehuda, this would suffice to avoid the prohibition of interest, and Rav Naḥman says: The halakha is in accordance with the opinion of R' Yehuda. Rav Kahana said to Rav Zevid: It was not stated by Rav Naḥman that the halakha is in accordance with the opinion of R' Yehuda, but rather it was stated that a single opinion is common to 3 rabbis: R' Yehuda; Rabban Shimon ben Gamliel; and R' Yosei, son of R' Yehuda. This does not establish the halakha in accordance with their statements, but on the contrary, they all hold one common opinion that is not accepted as the halakha.

הכי נמי מסתברא, דאי לא תימא הכי ⁠– למה ליה למיחשב ולמימר הלכה הלכה? לימא הלכה כרבי יהודה, דמיקל מכולהו.

The Talmud comments: This too stands to reason, as, if you do not say so, why did Rav Naḥman list them individually and say: The halakha is in accordance with the opinion of so-and-so, and the halakha is in accordance with the opinion of so-and-so? Instead let Rav Naḥman say simply: The halakha is in accordance with the opinion of R' Yehuda, as he is the most lenient of all of them, and their rulings can be derived from his. Since Rav Naḥman did not state this, it is reasonable to say that he was not issuing a ruling in accordance with their opinion, but simply clarifying that these 3 opinions are actually one.