Leviticus 27:30-33

And all the tithe of the land, whether of the seed of the land or of the fruit of the tree, is the LORD’s. It is holy to the LORD. If a man wants at all to redeem any of his tithes, he shall add one-fifth to it. And concerning the tithe of the herd or the flock, of whatever passes under the rod, the tenth one shall be holy to the LORD. He shall not inquire whether it is good or bad, nor shall he exchange it; and if he exchanges it at all, then both it and the one exchanged for it shall be holy; it shall not be redeemed.’ ”