Verses 15-19 (Leviticus 16:15-19)

When the priest had come out from the sprinkling the blood of the bullock before the mercy-seat, 1. He must next kill the goat which was the sin-offering for the people (Lev. 16:15) and go the third time into the holy of holies, to sprinkle the blood of the goat, as he had done that of the bullock; and thus he was to make atonement for the holy place (Lev. 16:16); that is, whereas the people by their sins had provoked God to take away those tokens of his favourable presence with them, and rendered even that holy place unfit to be the habitation of the holy God, atonement was hereby made for sin, that God, being reconciled to them, might continue with them. 2. He must then do the same for the outward part of the tabernacle that he had done for the inner room, by sprinkling the blood of the bullock first, and then that of the goat, without the veil, where the table and incense-altar stood, eight times each as before. The reason intimated is because the tabernacle remained among them in the midst of their uncleanness, Lev. 16:16. God would hereby show them how much their hearts needed to be purified, when even the tabernacle, only by standing in the midst of such an impure and sinful people, needed this expiation; and also that even their devotions and religious performances had much amiss in them, for which it was necessary that atonement should be made. During this solemnity, none of the inferior priests must come into the tabernacle (Lev. 16:17), but, by standing without, must own themselves unworthy and unfit to minister there, because their follies, and defects, and manifold impurities in their ministry, had made this expiation of the tabernacle necessary. 3. He must then put some of the blood, both of the bullock and of the goat mixed together, upon the horns of the altar that is before the Lord, Lev. 16:18, 19. It is certain that the altar of incense had this blood put upon it, for so it is expressly ordered (Exod. 30:10); but some think that this directs the high priest to the altar of burnt-offerings, for that also is here called the altar before the Lord (Lev. 16:12), because he is said to go out to it, and because it may be presumed that that also had need of an expiation; for to that the gifts and offerings of the children of Israel were all brought, from whose uncleanness the altar is here said to be hallowed.

- Matthew Henry's Complete Commentary