Bava Metzia1: 6
מָצָא שְׁטָרֵי חוֹב, אִם יֵשׁ בָּהֶן אַחֲרָיוּת נְכָסִים — לֹא יַחֲזִיר, שֶׁבֵּית דִּין נִפְרָעִין מֵהֶן. אֵין בָּהֶן אַחֲרָיוּת נְכָסִים — יַחֲזִיר, שֶׁאֵין בֵּית דִּין נִפְרָעִין מֵהֶן; דִּבְרֵי רַבִּי מֵאִיר. וַחֲכָמִים אוֹמְרִים: בֵּין כָּךְ וּבֵין כָּךְ לֹא יַחֲזִיר, מִפְּנֵי שֶׁבֵּית דִּין נִפְרָעִין מֵהֶן.
[If] one finds loan contracts [and] there is a lien on property in them, he should not return [them], since the court would ex-act payment with them. [If] there is no lien on property in them, he should return [them], since the court would not exact payment with them. [These are] the words of R’ Meir. The Sages, however, say: In either case he should not return [them], since the court would exact payment with them.
Bava Metzia1: 7
מָצָא גִטֵּי נָשִׁים, וְשִׁחְרוּרֵי עֲבָדִים, דִּיַּתִּיקִי, מַתָּנָה, וְשׁוֹבְרִים — הֲרֵי זֶה לֹא יַחֲזִיר, שֶׁאֲנִי אוֹמֵר: כְּתוּבִים הָיוּ, וְנִמְלַךְ עֲלֵיהֶם שֶׁלֹּא לִתְּנָם.
[If] one finds documents of divorce, [deeds of] emancipation of slaves, testaments, gifts, or receipts, he should not return them, for I say that [after] they were written, he reconsidered, [deciding] not to give them.