Leviticus 27
26 Ref "'Only the firstborn among animals, which is made a firstborn to Yahweh, no man may dedicate it; whether an ox or sheep, it is Yahweh's.
27 Ref If it is an unclean animal, then he shall buy it back according to your valuation, and shall add to it the fifth part of it: or if it isn't redeemed, then it shall be sold according to your valuation.