Leviticus 27:26-29

26But no one may consecrate a firstborn of the livestock, because a firstborn belongs to the LORD. Whether it is an ox or a sheep, it is the LORD’s. 27But if it is among the unclean animals, then he may redeem it according to your valuation and add a fifth of its value. If it is not redeemed, then it shall be sold according to your valuation.

28Nothing that a man sets apart1 to the LORD from all he owns—whether a man, an animal, or his inherited land—can be sold or redeemed; everything so devoted is most holy to the LORD.

29No person set apart for destruction may be ransomed; he must surely be put to death.