Numbers 18:15-20

15Every thing that openeth the womb in all flesh, which they bring to the LORD, whether of men or beasts, shall be thine: nevertheless the firstborn of man shalt thou surely redeem, and the firstling of unclean beasts shalt thou redeem. 16And those that are to be redeemed from a month old shalt thou redeem, according to thy estimation, for the money of five shekels, after the shekel of the sanctuary, which is twenty gerahs. 17But the firstling of a cow, or the firstling of a sheep, or the firstling of a goat, thou shalt not redeem; they are holy: thou shalt sprinkle their blood upon the altar, and shalt burn their fat for an offering made by fire, for a sweet savour to the LORD. 18And the flesh of them shall be thine, as the wave breast and as the right shoulder are thine. 19All the heave offerings of the holy things, which the children of Israel offer to the LORD, have I given to thee, and to thy sons and thy daughters with thee, by a statute for ever: it is a covenant of salt for ever before the LORD to thee and to thy seed with thee.

20And the LORD spoke to Aaron, Thou shalt have no inheritance in their land, neither shalt thou have any part among them: I am thy part and thy inheritance among the children of Israel.