Numbers 18:17-18

¹⁷But the firstborn of an ox or the firstborn of a sheep or the firstborn of a goat, you shall not redeem; they are holy. You 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 meat shall be yours; it shall be yours like the breast of a wave offering and like the right thigh.