Leviticus 27:8-12

⁸But if he be poorer than thy estimation, then he shall present himself before the priest, and the priest shall value him; according to his ability that vowed shall the priest value him.

⁹And if it be a beast, whereof men bring an offering unto the Lord, all that any man giveth of such unto the Lord shall be holy.

¹⁰He 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 it and the exchange thereof shall be holy.

¹¹And if it be any unclean beast, of which they do not offer a sacrifice unto the Lord, then he shall present the beast before the priest:

¹²and the priest shall value it, whether it be good or bad: as thou valuest it, who art the priest, so shall it be.