וְכֵ֧ן תַּעֲשֶׂ֣ה לַחֲמֹר֗וֹ וְכֵ֣ן תַּעֲשֶׂה֮ לְשִׂמְלָתוֹ֒ וְכֵ֣ן תַּעֲשֶׂ֜ה לְכָל־אֲבֵדַ֥ת אָחִ֛יךָ אֲשֶׁר־תֹּאבַ֥ד מִמֶּ֖נּוּ וּמְצָאתָ֑הּ לֹ֥א תוּכַ֖ל לְהִתְעַלֵּֽם׃ (ס)
나귀라도 그리하고 의복이라도 그리하고 무릇 형제의 잃은 아무 것이든지 네가 얻거든 다 그리하고 못본체 하지 말 것이며
Rashi
לא תוכל להתעלם THOU MAYEST NOT HIDE THYSELF — i.e. You must not cover your eyes, pretending not to see it.
Ibn Ezra
The phrase you cannot is here to be interpreted as it is in similar instances [cf. comment on 21: 16].
Sforno
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.