וְכֵ֧ן תַּעֲשֶׂ֣ה לַחֲמֹר֗וֹ וְכֵ֣ן תַּעֲשֶׂה֮ לְשִׂמְלָתוֹ֒ וְכֵ֣ן תַּעֲשֶׂ֜ה לְכָל־אֲבֵדַ֥ת אָחִ֛יךָ אֲשֶׁר־תֹּאבַ֥ד מִמֶּ֖נּוּ וּמְצָאתָ֑הּ לֹ֥א תוּכַ֖ל לְהִתְעַלֵּֽם׃ (ס)
И так сделаешь с его задницей; и так поступай с одеждой его; и так поступай со всеми потерянными вещами брата твоего's, которые он потерял, а ты нашел; ты не можешь прятаться.
Rashi on Deuteronomy
לא תוכל להתעלם THOU MAYEST NOT HIDE THYSELF — i.e. You must not cover your eyes, pretending not to see it.
Sforno on Deuteronomy
וכן תעשה לשמלתו, even though such a find is far less likely to occur, so that you might consider it as having been abandoned on purpose.
Tur HaArokh
וכן תעשה לחמורו, ...לשמלתו...ולכל אבדת אחיך, “you are to deal in a similar manner with an ass, a garment, or any other object your brother has apparently lost.” The Torah lists different categories of possessions, some that need feeding, others that are relatively inexpensive and do not represent a great loss if the loser does not recover them. Our sages also derive from the words עד דרוש אחיך, “until your brother request said object,” that in order to claim such “lost” property the claimant must furnish proof that these objects are really his.