Leviticus 16:11-13

11“When Aaron presents the bull for his sin offering and makes atonement for himself and his household, he will slaughter the bull for his sin offering.

12Then he is to take a firepan full of blazing coals from the altar before the Lord and two handfuls of finely ground fragrant incense, and bring them inside the curtain.

13He is to put the incense on the fire before the Lord, so that the cloud of incense covers the mercy seat that is over the testimony, or else he will die.