Leviticus 27:10-12

American Standard Version

¹⁰ He shall not alter it, nor change it, a good for a bad, or a bad for a good: and if he shall at all change beast for beast, then both it and that for which it is changed shall be holy. ¹¹ And if it be any unclean beast, of which they do not offer an oblation unto Jehovah, then he shall set the beast before the priest; ¹² and the priest shall value it, whether it be good or bad: as thou the priest valuest it, so shall it be.