Reference for Bava Metzia 35:12
ואפי' במקום שהשיירות מצויות והוא שהוחזקו שני יוסף בן שמעון בעיר אחת
and have written on it: This bill of divorcement has been torn by us, not because it is an invalid bill, but to prevent it being used for the purpose of exacting payment a second time,' [the answer would be:] Do all who exact payment [of a debt] exact such payment in a Court of Law?<span class="x" onmousemove="('comment',' It is only when payment is made in a Court of Law that one can expect the document to be endorsed in the way suggested, but people do not always pay their debts in Court. So that even if it be admitted that the mere production of the bill of divorcement entitles the woman to demand payment of the amount of the Kethubah just as if the amount were stated in the bill, one could not maintain that the husband would not be believed if he pleaded 'I have paid already,' seeing that he has good reason for not having had destroyed the bill of divorcement on payment. It must therefore be assumed that the reason why payment of the Kethubah can be enforced against the plea of the husband is that it is based on an enactment of the Courts, and in accordance with the dictum of R. Johanan given above. ');"><sup>12</sup></span>