Albert Barnes Commentary Leviticus 4:5

"And the anointed priest shall take of the blood of the bullock, and bring it to the tent of meeting:" — Leviticus 4:5 (ASV)

The treatment of the blood was special in the sin-offerings. In the inferior sin-offerings it was smeared on the horns of the altar of burnt-offering (Leviticus 4:25, 30, 34), while in this offering for the high priest, and in that for the nation, the high priest himself sprinkled the blood seven times within the tabernacle and smeared it on the horns of the altar of incense (Leviticus 4:6–7, 17-18). The different modes of sprinkling appear to have marked successive degrees of consecration in advancing from the altar of burnt-offering to the presence of Yahweh within the veil.