Leviticus 27:9-13

9‘Now if it is an animal of the kind which men can present as an offering to the Lord, any such that one gives to the Lord shall be holy.

10He shall not replace it or exchange it, a good for a bad, or a bad for a good; but if he does exchange an animal for an animal, then both the original offering and its substitute shall be holy.

11If it is any unclean animal of the kind which men do not present as an offering to the Lord, then he shall bring the animal before the priest,

12and the priest shall value it as either good or bad; it shall be as you, the priest, value it.

13But if he ever wishes to redeem it, then he shall add one-fifth of it to your valuation.