Leviticus 3:2

And he shall lay his hand on the head of his offering and kill it at the entrance of the tent of meeting , and Aaron’s sons the priests shall throw the blood against the sides of the altar .

You are to lay your hand on the head of your offering and slaughter it at the entrance to the tent of meeting. Then Aaron`s sons the priests shall splash the blood against the sides of the altar.

And he shall lay his hand upon the head of his offering, and kill it at the door of the tabernacle of the congregation : and Aaron's sons the priests shall sprinkle the blood upon the altar round about.