Numbers 18:12, 17

“And I give you all the best olive oil and all the best new wine and grain. This is what the Israelites give to me, the LORD, from the first crops they harvest.

“But you must not make a payment for the firstborn ox or sheep or goat. Those animals are holy. Sprinkle their blood on the altar and burn their fat as an offering made by fire. The smell is pleasing to the LORD.