Leviticus 16:18 - Matthew Poole's English Annotations on the Holy Bible

Unto the altar, to wit, the altar of incense, where the blood of sacrifices was to be put, Leviticus 4:7; and particularly the blood of the sin-offerings offered upon this day of atonement, Exodus 30:10; and which is most truly and properly said to be before the Lord, i.e. before the place where God in special manner dwelt, to wit, the holy of holies. Some understand it of the altar of burnt-offerings, because he is said to go out to it. But that going out relates not to the tabernacle, but to the holy of holies, into which he was said to go in, Leviticus 16:17. Add to this, that this altar which is atoned by the high priest seems to be in that place where he only might now come, and therefore in the holy place, called here the tabernacle, from which all other priests were for this day excluded, whereas the altar of burnt-offerings was without the holy place or tabernacle, to wit, at the door of it, and in the court of the priests.