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. {firstling of: Heb. firstborn, etc} 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.