Reference for Bava Batra 61:9

זה אומר של אבותי וזה אומר של אבותי האי אייתי סהדי דאבהתיה ואכלה שני חזקה והאי אייתי סהדי דאכלה שני חזקה

also that if a man makes certain statements outside [the court] and then wants to plead something quite different in court, he may do so, because a man often does not wish to state his case save in actual court. Amemar said: I am a Nehardean, and I hold that pleas may be altered. And such is the accepted ruling, that pleas may be altered.

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