Numbers 3:48,51 And you shall give the money, with which the odd number of them is to be redeemed, to Aaron and to his sons. Torrey's Topical Textbook
Numbers 18:15,16 Every thing that opens the matrix in all flesh, which they bring to the LORD, whether it be of men or beasts, shall be yours: nevertheless the firstborn of man shall you surely redeem, and the firstling of unclean beasts shall you redeem. Torrey's Topical Textbook