Leviticus 27:30-33

‘Thus all the tithe of the land, of the seed of the land or of the fruit of the tree, is the LORD’S; it is holy to the LORD. If, therefore, a man wishes to redeem part of his tithe, he shall add to it one-fifth of it. For every tenth part of herd or flock, whatever passes under the rod, the tenth one shall be holy to the LORD. He is not to be concerned whether it is good or bad, nor shall he exchange it; or if he does exchange it, then both it and its substitute shall become holy. It shall not be redeemed.’ ”