Leviticus 27:26-29

26“But the firstborn among animals, which is made a firstborn to Adonai, may not be dedicated by anyone. Whether an ox or sheep, it belongs to Adonai.

27If it is an unclean animal, then he is to buy it back according to your valuation, and add a fifth of the value to it. But if it is not redeemed, then it is to be sold according to your valuation.

28“Nevertheless, no devoted thing which a man sets apart from all that he has for Adonai, whether man or animal, or from the field of his possession, may be sold or redeemed. Every devoted thing is most holy to Adonai.

29“No one who may be set apart from men for destruction is to be ransomed. He is surely to be put to death.