Numbers 18:15-17

International Standard Version

¹⁵ Everything that opens the womb, any living thing that they bring to the Lord—whether from human beings or animals—are for you. Just be sure that you redeem the firstborn of people and the firstborn of unclean animals. ¹⁶ Those that can be redeemed, you are to redeem at the age of one month, based on your estimate—for five shekels of silver, according to the shekel of the sanctuary, that is, for 20 gerahs. ¹⁷ But you are not to redeem the firstborn of a cow, sheep, or a female goat. They are holy. You are to sprinkle their blood on the altar and burn their fat for an offering made by fire, a pleasing aroma to the Lord.