Leviticus 16:2-6

The LORD said to Moses, “Warn your brother, Aaron, not to enter the Most Holy Place behind the inner curtain whenever he chooses; if he does, he will die. For the Ark’s cover—the place of atonement—is there, and I myself am present in the cloud above the atonement cover. “When Aaron enters the sanctuary area, he must follow these instructions fully. He must bring a young bull for a sin offering and a ram for a burnt offering. He must put on his linen tunic and the linen undergarments worn next to his body. He must tie the linen sash around his waist and put the linen turban on his head. These are sacred garments, so he must bathe himself in water before he puts them on. Aaron must take from the community of Israel two male goats for a sin offering and a ram for a burnt offering. “Aaron will present his own bull as a sin offering to purify himself and his family, making them right with the LORD.