TSK · Numbers 18:17

He must lay his hand on the head of his offering and slaughter it at the entrance of the Meeting Tent, and the sons of Aaron, the priests, must splash the blood against the altar’s sides.

Giving God the Best You must set apart for the LORD your God every firstborn male born to your herds and flocks. You must not work the firstborn of your bulls or shear the firstborn of your flocks.