Leviticus 27:9-13

9And if it be a beast whereof men bring an offering unto Jehovah, all that they give of such unto Jehovah shall be holy.

10They shall not alter it nor change it, a good for a bad, or a bad for a good; and if he 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 bring an offering unto Jehovah, then he shall present the beast before the priest;

12and the priest shall value it, [judging] between good and bad: according to the valuation of the priest, so shall it be.

13And if they will in any wise redeem it, then they shall add a fifth [part] thereof unto thy valuation.