וְנָתַתָּ֣ה הַכֶּ֔סֶף לְאַהֲרֹ֖ן וּלְבָנָ֑יו פְּדוּיֵ֕י הָעֹדְפִ֖ים בָּהֶֽם׃
And thou shalt give the money wherewith they that remain over of them are redeemed unto Aaron and to his sons.’
Read midrashic interpretation of Numbers 3:48: and classical rabbinic exegesis.