EXO 30:10

10 One time every year Aaron must perform the ritual for making this altar pure. He must do it by putting on its four projections some of the blood from the animal that was sacrificed ◄to remove the guilt of the people’s sins/so that the people would no longer be guilty for sins►. This ritual is to be done by Aaron and his descendants throughout all future generations. This altar must be completely dedicated to me, Yahweh.”