A braita states that if a receipt is found saying that the husband (or his heirs) paid his ex-wife the money from her ketuba, , if the woman agrees, we return it to the husband as proof he paid. Why are we not concerned that perhaps the the money was not repaid on the date written on the receipt, but was paid later, and the couple is conspiring to retrieve her ketuba that she sold after the date written on the receipt, but before the actual payment? Rava and Abaye each suggest answers. The Mishna lists types of documents that if found on the street can be returned as there is no concern that one could collect money not due to them. The list includes igrot shum, documents assessing land of a debtor to be seized by a creditor, the commitment of a husband to pay for food of his wife's daughter, documents attesting that a chalitza or mi'un was performed, and others. If documents were bundled up together or found in a way that one could claim it by offering identifiable markings (simanim), they can be retrieved as well. If a receipt of payments is found, even by the creditor, it is given to the debtor as proof of payment. Rav Huna did not permit a get found in the street to be used as he was concerned that perhaps it belonged to people with the same names who lived in a city with the same name as written in the get. Raba disagreed with Rav Huna based on our Mishna which permits returning documents ratified by the court and is not concerned that the documents belonged to other people. This led to an argument between Raba and Amram who responded disrespectfully to the other, which then caused a pillar to break in Rav's beit midrash. The Gemara defines a number of the objects mentioned in the Mishna - chafisa, dluskima, and documents that are krukhin and agudim. One who finds a bunch of documents bundled together announces that he/she found documents and the one who lost them can retrieve them by identifying how many and how they are bound. Rav ruled that if a receipt attesting to payment of a loan is found with the creditor's documents, we cannot assume it was paid as the creditor may have written it so that when the borrower is ready to pay, the receipt will be ready. However, this contradicts a ruling in our Mishna that a simpon (receipt of payment) found in the creditor's papers is returned to the debtor. To resolve this, they bring a differentiation Rav Safra made regarding a different source that it depends on if it was found with ripped papers of the creditor or with the creditor's regular papers. Two other Mishnayot are brought to raise the same type of difficulty against this statement of Rav and are all resolved in the same manner.