Numbers 18:15-17

¹⁵every one opening a womb of all flesh which they bring near to Jehovah, among man and among beast, is thine; only, thou dost certainly ransom the first-born of man, and the firstling of the unclean beast thou dost ransom.

¹⁶'And their ransomed ones from a son of a month, thou dost ransom with thy valuation, of silver, five shekels, by the shekel of the sanctuary, twenty gerahs it is.

¹⁷'Only, the firstling of a cow, or the firstling of a sheep, or the firstling of a goat, thou dost not ransom, holy they are: their blood thou dost sprinkle on the altar, and of their fat thou makest perfume, a fire-offering of sweet fragrance to Jehovah,