Bava Batra 128B

תיובתא דכולהו! תיובתא.

The Talmud concludes: The refutation of the opinions of all the amora’im who held that a person who became blind after witnessing a matter can, in certain cases, testify about it, is indeed a conclusive refutation.

שלח רבי אבא לרב יוסף בר חמא: האומר על תינוק בין הבנים ⁠– נאמן. ורבי יוחנן אמר: אינו נאמן.

§ R' Abba sent another ruling to Rav Yosef bar Ḥama: One who says something concerning one child among his sons is deemed credible, and R' Yoḥanan says that he is not deemed credible.

מאי קאמר? אמר אביי: הכי קאמר, האומר על תינוק בין הבנים: ״יירש כל נכסי״⁠ – נאמן, כרבי יוחנן בן ברוקה. ורבי יוחנן אמר: אינו נאמן, כרבנן.

The Talmud asks: What is R' Abba saying? Abaye said that this is what R' Abba is saying: One who says concerning one child among his sons: He should inherit all my property, is deemed credible, in accordance with the opinion of R' Yoḥanan ben Beroka, who holds that one can bequeath all his property to one of his heirs (130a). And R' Yoḥanan says that he is not deemed credible, in accordance with the opinion of the Rabbis, who disagree with R' Yoḥanan ben Beroka.

מתקיף לה רבא: האי ״נאמן״ ו״אינו נאמן״?! ״יירש״ ו״לא יירש״ מבעיא ליה!

Rava objects to this explanation: According to Abaye’s explanation, this wording: Is deemed credible, and: He is not deemed credible, is not precise; he should have employed the terms: should inherit, and: should not inherit, as the issue is the ability of the father to specify who will inherit from him, not his credibility.

אלא אמר רבא: הכי קאמר, האומר על תינוק בין הבנים: ״בכור הוא״⁠ – נאמן, כרבי יהודה. ורבי יוחנן אמר: אינו נאמן, כרבנן.

Rather, Rava said that this is what R' Abba is saying: One who says about one child among his sons that he is his firstborn is deemed credible, in accordance with the opinion of R' Yehuda (127b); and R' Yoḥanan says that he is not deemed credible, in accordance with the opinion of the Rabbis, who disagree with R' Yehuda.