Leviticus 27:8-10

Evangelical Heritage Version

⁸ But if anyone making a dedication is too poor to pay that standard value, he shall appear before the priest with the dedicated person, and the priest shall assess a substitute valuation for the person. The priest shall assess a value on the basis of what the person who has made the vow can afford.

⁹ If what is vowed is livestock which is acceptable as an offering to the Lord, anything that a person dedicates to the Lord is set apart as holy. ¹⁰ He may not exchange it or substitute another for it, either good for bad, or bad for good. If he substitutes one animal for another, both the animal and its substitute are set aside as holy.