Nedarim 6A

דאין אדם מגרש את אשת חבירו, אבל בעלמא ⁠— מי שמעת להו?

as a man does not divorce the wife of his fellow, so it is obvious that he is writing the bill of divorce to his wife. However, did you hear them state generally that ambiguous intimations are valid intimations?

מיתיבי: ״הרי הוא עלי״, ״הרי זה [עלי]״⁠ — אסור, מפני שהוא יד לקרבן. טעמא דאמר ״עלי״⁠ — הוא דאסור, אבל לא אמר ״עלי״⁠ — לא. תיובתא דאביי!

The Talmud raises an objection based upon the following baraita: If one says with regard to an object lying before him: It is upon me, or: This is hereby upon me, it is forbidden, because it is an intimation that he is rendering the object forbidden to himself like an offering. This baraita indicates that the reason it is forbidden is that he specifically said: Upon me. However, if he did not say: Upon me, no, it is not forbidden, because this expression is an ambiguous intimation. This is a conclusive refutation of the opinion of Abaye, who holds that even ambiguous intimations are valid intimations.

אמר לך אביי: טעמא דאמר ״עלי״⁠ — הוא דאסור. אבל אמר ״הרי הוא״, ולא אמר ״עלי״, ״הרי הוא דהפקר״ ״הרי הוא דצדקה״ קאמר. והא ״מפני שהוא יד לקרבן״ קתני!

The Talmud answers: Abaye could have said to you that the reason it is forbidden is that he specifically said: Upon me. However, if he said: It is hereby, and did not say: Upon me, his statement is not considered an intimation of a vow at all, as he could have been saying: It is hereby ownerless property, or: It is hereby charity. The Talmud asks: But the baraita teaches that the object is forbidden because his statement is an intimation that he is rendering the object forbidden to himself like an offering. With regard to consecrating an offering, even the statement: This is, without the additional phrase: Upon me, is considered an intimation. Nevertheless, the baraita indicates that if one does not say: Upon me, the vow does not take effect. This must be because an ambiguous intimation is not a vow.