Leviticus 27:27-31

²⁷And if it be an unclean animal, then he shall redeem it according to its valuation, and add one fifth thereto: or if it be not redeemed, then it shall be sold according to its valuation.

²⁸Nevertheless, no devoted thing which a man shall have devoted before the Lord of all that he hath of man or of beast and of the field of his possession may be sold or redeemed; every devoted thing is most sacred before the Lord.

²⁹No devoted one who is devoted (or accursed) of men, (as the criminal doomed to death,) shall be redeemed; being slain, he shall be killed.

³⁰And 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 sacred before the Lord.

³¹But if a man will redeem any of his tithe, a fifth shall be add upon it.