Reference for Bava Metzia 32:12
אלא אמר רבא התם היינו טעמא דאמרי איהו הוא דאפסיד אנפשיה דבעידנא דפרעיה אבעי ליה למקרעיה לשטריה א"נ למכתב שטרא אחרינא עילויה
And if [this were objected to] on the ground that [the loan] may [in the meantime] have been repaid [the objection would not be valid either] because we are not afraid of repayment [having taken place], as [we assume that] if [the borrower] had repaid [the loan] he would have torn up [the deed]. R. Nahman said: My father was among the scribes of Mar Samuel's court when I was about six or seven years old, and I remember that they used to proclaim: 'Deeds of transfer which are found in the street should be returned to their owners.' R. Amram said: We have also learned so [in a Mishnah]: All documents executed by a court of law shall be returned [when found],<span class="x" onmousemove="('comment',' Infra 200. This would include a note of indebtedness endorsed by the court and excluding the possibility of the loan not having been granted (cf. B.K. 112b) which would show that as long as we are sure that the loan was granted we do not suspect its validity on the ground that the loan may have been repaid. ');"><sup>12</sup></span>