Tosefta על כתובות 7:8

A man who says to his fellow: "Betroth to me your daughter with the understanding that she has no defects", and he said to him: "My daughter is sickly", [or] "She is insane", "She is epileptic", "She is dull-witted", "She has another defect" and he inserts it amongst [other] defects [that she does not have]—this is a mistaken purchase. [If he said,] "She has these defects and another one as well" [which he didn't specify]—this is not a mistaken purchase. Rabbi Meir concedes (sic!, text from Ehrfurt manuscript) [to Hakhamim, see Mishnah Ketubot 7:8] regarding defects that she was born with that, even though she is with her husband, her father needs to bring evidence [that she was born with them]. If he brought her in without stipulation and it turned she had defects and vows, the ketubah stands.