John Wesley on Leviticus 16:18

The altar before the Lord - That is, the altar of incense, where the blood of sacrifices was to be put, particularly the blood of the sin - offerings offered upon this day of atonement, and which is most properly said to be before the Lord, that is, before the place where God in a special manner dwelt. His going out relates to the holy of holies, into which he was said to go in, Lev 16:17.