Leviticus 10:19

10:19 But Aaron spoke to Moses, “See here! Just today they presented their sin offering and their burnt offering before the Lord and such things as these have happened to me! If I had eaten a sin offering today would the Lord have been pleased?”

Leviticus 16:2

16:2 and the Lord said to Moses: “Tell Aaron your brother that he must not enter at any time into the holy place inside the veil-canopy in front of the atonement plate that is on the ark so that he may not die, for I will appear in the cloud over the atonement plate.