Numbers 18:17-19

17But 1the firstborn of an ox or the firstborn of a sheep or the firstborn of a goat, you shall not redeem; they are holy. 2You shall sprinkle their blood on the altar and shall offer up their fat in smoke as an offering by fire, for a soothing aroma to the Lord.

18Their 3meat shall be yours; it shall be yours like the 4breast of a wave offering and like the right thigh.

195All the offerings of the holy gifts, which the sons of Israel offer to the Lord, I have given to you and your sons and your daughters with you, as a perpetual allotment. It is 6an everlasting covenant of salt before the Lord to you and your 7descendants with you.”