Leviticus 27:30-33

30Thus any tithe from the land, whether from the seed of the land or the fruit of the trees, belongs to the LORD; it is holy to the LORD. 31If a man wishes to redeem part of his tithe, he must add a fifth to its value.

32Every tenth animal from the herd or flock that passes under the shepherd’s rod will be holy to the LORD. 33He must not inspect whether it is good or bad, and he shall not make any substitution. But if he does make a substitution, both the animal and its substitute shall become holy; they cannot be redeemed.’”