Leviticus 16:3

Thus shall Aaron come into the holy [place],.... The most holy place; and this was after he had offered the daily sacrifice of the morning, and had performed the rest of the service then done, as Gersom observes; such as burning the incense and trimming the lamps, for no offering preceded the daily sacrifice:

with a young bullock for a sin offering, and a ram for a burnt offering; which were both for himself and his family; and such were the weakness, imperfection, and insufficiency of the Levitical priesthood, and priests, that they were obliged first to offer for their own sins, and then for the sins of the people: the meaning is not, as Aben Ezra says, that he should bring the bullock into the holy place, only that he should first give of his own a bullock for a sin offering, to atone for himself, and for the priests; nor could it be the body of the bullock he brought, only the blood of it into the most holy place, where he entered not without blood, first with the blood of the bullock, and then with the blood of the goat; for the body of the bullock for a sin offering was burnt without the camp, and the body of the ram for the burnt offering was burnt upon the altar of burnt offering; see Hebrews 9:7.