Leviticus 27:26-29

26“‘Surely no man may consecrate a firstborn that already belongs to the Lord as a firstborn among the animals; whether it is an ox or a sheep, it belongs to the Lord.

27If, however, it is among the unclean animals, he may ransom it according to its conversion value and must add one fifth to it, but if it is not redeemed it must be sold according to its conversion value.

28“‘Surely anything which a man permanently dedicates to the Lord from all that belongs to him, whether from people, animals, or his landed property, must be neither sold nor redeemed; anything permanently dedicated is most holy to the Lord.

29Any human being who is permanently dedicated must not be ransomed; such a person must be put to death.