Leviticus 27:30-33

30“‘Any tithe of the land, from the grain of the land or from the fruit of the trees, belongs to the Lord; it is holy to the Lord.

31If a man redeems part of his tithe, however, he must add one fifth to it.

32All the tithe of herd or flock, everything which passes under the rod, the tenth one will be holy to the Lord.

33The owner must not examine the animals to distinguish between good and bad, and he must not exchange it. If, however, he does exchange it, both the original animal and its substitute will be holy. It must not be redeemed.’”