Numbers 18:14-16 New English Translation (NET Bible)
14 “Everything devoted[a] in Israel will be yours. 15 The firstborn of every womb which they present to the Lord, whether human or animal, will be yours. Nevertheless, the firstborn sons you must redeem,[b] and the firstborn males of unclean animals you must redeem. 16 And those that must be redeemed you are to redeem when they are a month old, according to your estimation, for five shekels of silver according to the sanctuary shekel (which is twenty gerahs).