Leviticus 27:8-12

⁸But if he be too poor (for the sum of) his valuation, then he shall stand before the priest, and the priest shall make valuation for him upon the word of that which the hand of him who maketh the vow may possess; so shall the priest make his estimate.

⁹And if it be an animal of which (some portion) will be offered an oblation before the Lord, all that he giveth of it before the Lord shall be sacred;

¹⁰He shall not alter it or change it, good for bad, or bad for good; and if he will indeed change animal for animal, both it and that for which it is changed shall be sacred.

¹¹And if it be any unclean animal, of which none may be offered an oblation before the Lord, he shall present the animal before the priest,

¹²And the priest shall value it, whether good or bad; according to the estimate of the priest so shall it be.