Leviticus 27:8-10

King James Version

⁸ But 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.

⁹ And 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.

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 it and the exchange thereof shall be holy.