Leviticus 27:9-13 - Redemption Of Vowed Animals
9 "'If it be of the beasts of which men bring an offering unto the LORD: all that any man giveth of such unto the LORD, shall be holy. 10 He may not alter it nor change it: a good for a bad or a bad for good. If he change beast for beast, then both the same beast and it also wherewith it was changed shall be holy.
11 If it be any manner of unclean beast of which men may not offer unto the LORD, let him bring the beast before the priest 12 and let the priest value it. And whether it be good or bad as the priest setteth it, so shall it be. 13 And if he will buy it again, let him give the fifth part more to that it was set at.