Leviticus 27:9-13

9“‘If what is vowed is a kind of animal from which an offering may be presented to the Lord, anything which he gives to the Lord from this kind of animal will be holy.

10He must not replace or exchange it, good for bad or bad for good, and if he does indeed exchange one animal for another animal, then both the original animal and its substitute will be holy.

11If what is vowed is an unclean animal from which an offering must not be presented to the Lord, then he must stand the animal before the priest,

12and the priest will establish its conversion value, whether good or bad. According to the assessed conversion value of the priest, thus it will be.

13If, however, the person who made the vow redeems the animal, he must add one fifth to its conversion value.