Numbers 18:17-19

New Revised Standard Version Catholic Edition

¹⁷ But the firstborn of a cow, or the firstborn of a sheep, or the firstborn of a goat, you shall not redeem; they are holy. You shall dash their blood on the altar, and shall turn their fat into smoke as an offering by fire for a pleasing odor to the Lord; ¹⁸ but their flesh shall be yours, just as the breast that is elevated and as the right thigh are yours. ¹⁹ All the holy offerings that the Israelites present to the Lord I have given to you, together with your sons and daughters, as a perpetual due; it is a covenant of salt forever before the Lord for you and your descendants as well.