Numbers 18:15-20

15Everything that breaketh open the womb of all flesh, which they present to Jehovah, of men or of beasts, shall be thine; nevertheless the firstborn of man shalt thou in any case ransom, and the firstborn of unclean beasts shalt thou ransom.

16And those that are to be ransomed from a month old shalt thou ransom, according to thy valuation, for the money of five shekels, after the shekel of the sanctuary, which is twenty gerahs.

17But the firstborn of a cow, or the firstborn of a sheep, or the firstborn of a goat, thou shalt not ransom: they are holy. Thou shalt sprinkle their blood on the altar, and their fat shalt thou burn as an offering by fire for a sweet odour to Jehovah.

18And their flesh shall be thine; as the wave-breast and as the right shoulder shall it be thine.

19All the heave-offerings of the holy things, which the children of Israel offer to Jehovah, have I given thee, and to thy sons and to thy daughters with thee, by an everlasting statute: it shall be an everlasting covenant of salt before Jehovah unto thee and thy seed with thee.

20And Jehovah said to Aaron, In their land thou shalt have no inheritance, neither shalt thou have any portion among them: I am thy portion and thine inheritance among the children of Israel.