Leviticus 27:26-27

Only the firstling of the beasts, which should be the LORD's firstling, no man shall sanctify it; whether it be ox, or sheep: it is the LORD's. And if it be of an unclean beast, then he shall redeem it according to thine estimation, and shall add a fifth part of it thereto: or if it be not redeemed, then it shall be sold according to thy estimation.