Ketubot 76B

כלה בבית אביה, מי דמי? התם ⁠— מייתי אב ראיה ומפיק, הכא ⁠— מייתי בעל החמור ראיה ומוקים.

that his proof is from the halakha with regard to a bride who is still in her father’s house, when the burden of proof is upon the father, is it comparable? There, the father brings proof and takes money away from the husband, whereas here, the owner of the donkey brings proof and maintains possession of the cow. Consequently, perhaps this case is different, and he should not be obliged to provide proof.

אמר רבי אבא: כלה בבית חמיה. ואכתי לא דמי: התם ⁠— בעל מייתי ראיה ומרע ליה לחזקיה דאב, הכא ⁠— בעל החמור מייתי ראיה ומוקים חזקיה בידיה.

R' Abba said: The proof is from the case of a bride in her father-in-law’s house, that is, one who has entered her husband’s domain. The Talmud raises a difficulty: And yet the cases are still not comparable: There, the husband brings proof and undermines the presumption that was in favor of the father, i.e., the presumptive status of the daughter’s body, whereas here, the owner of the donkey brings proof and thereby maintains the presumptive status of the donkey’s body and consequently maintains the cow in his possession. Perhaps, therefore, he should not have to bring proof.

אמר רב נחמן בר יצחק: כלה בבית אביה, ולקידושין.

Rav Naḥman bar Yitzḥak said: Shmuel’s proof is from the halakha of a bride in her father’s house, but with regard to the money used for betrothal, not for the marriage contract. The father must bring proof in order to retain the betrothal money.

ולא תימא אליבא דמאן דאמר קדושין לאו לטיבועין ניתנו. אלא אפילו למאן דאמר קדושין לטיבועין ניתנו ⁠— הני מילי קידושי ודאי, אבל קידושי טעות, אי מייתי ראיה ⁠— אין, אי לא ⁠— לא.

Rav Naḥman bar Yitzḥak explains: And do not say that this is only according to the one who says in general that betrothal money was not given with the understanding that it is to be lost, that is, the money was handed over only for the purpose of betrothal and it must be returned if the betrothal is canceled. Rather, say that this is even according to the one who says that in the case of betrothal money that was given to be lost, this applies only to a betrothal whose status is certain. According to this opinion, if a husband later divorces his wife or dies she does not have to restore the betrothal money. But with regard to a mistaken betrothal, if the father brings proof then yes, he may keep the money; if he does not bring proof he may not retain ownership of the betrothal money. This supports Shmuel’s opinion that in an uncertain case the one in possession of the money must bring proof in order to retain his ownership.