תלמוד על סנהדרין 8:6

It was stated “compromised”. Not that she reduced her ketubah¹⁶⁷This statement is quoted in Šebuot 7:7 (38a 1. 25), Sanhedrin 8:6 (26b 1. 49); Babli 87b.. If her ketubah was 200 but she claims a mina, she is paid without an oath¹⁶⁸In the Babli, this is made more explicit: If her ketubah was 1000 zuz, the husband claims that it was paid but he has no receipt, the divorced wife states that she received nothing but that her claim was only a mina, this is not conceding part of the husband’s claim (cf. Note 166) and she collects without an oath. It seems that the Yerushalmi would agree to that interpretation.
On documents which show that 200 zuz written in the ketubah might mean 100 zuz in actual money (and the standards by which the value of a zuz is determined), cf. M. A. Friedman, loc. cit. Note 87.. What is the difference between one who compromises and one who claims less? Rebbi Ḥanina said, if she compromises there was a transaction between them¹⁶⁹Therefore, the oath is required if only to protect creditors with claims against the estate.; if she claims less there was no transaction between them¹⁷⁰At least, there is no presumption of any transactions between her and her husband regarding her ketubah during her marriage. Therefore, anybody claiming that there was such a transaction in order to impose an oath on the widow would have to prove his case in court..