Leviticus 27:26-29

26"But a firstborn of animals, which as a firstborn belongs to the Lord, no man may dedicate; whether ox or sheep, it is the Lord's.

27And if it is an unclean animal, then he shall buy it back at the valuation, and add a fifth to it; or, if it is not redeemed, it shall be sold at the valuation.

28"But no devoted thing that a man devotes to the Lord, of anything that he has, whether man or beast, or of his inherited field, shall be sold or redeemed; every devoted thing is most holy to the Lord.

29No one devoted, who is to be devoted for destruction from mankind, shall be ransomed; he shall surely be put to death.