(Mishnah): If a borrower paid back part of his loan - R. Yehuda says that he should exchange it (for a new document with the reduced amount); R. Yosi says that the lender should write him a receipt.

R. Yehuda: You are obligating the borrower to constantly have to protect it from the mice.

R. Yosi: This way is better for him, otherwise you are weakening the lender's strength (by replacing the document, as the property of the borrower will now be on lean only from the date of the later document).

(Gemara) - Rav: When the Mishnah taught (according to R. Yehuda that he should exchange it), the lender must go to Beis Din to make a document rather than do it privately through witnesses.

Beraisa (R. Chiya): One does not need to do it through Beis Din.

R. Yirmiyah: If Rav would have heard the Beraisa of R. Chiya, he would have retracted.

If there was a case when the borrower partially paid back the loan and the borrower said to the lender, "I, Ploni son of Ploni, borrowed from you, Ploni, and Ploni was the guarantor"...

Rav: He must also mention the date of the first document on the second document.

Shmuel: He does not need to mention it.

Beraisa (R. Chiya): He does not need to mention it.

Question (R. Yochanan): According to Rav that it must be mentioned, how could R. Yosi have said in the Mishnah that you are weakening the lender's strength (by replacing the document, as the property of the borrower will now only be on lean from the date of the later document)?