The word “horn” (qěrěn) occurs for the first time in the context of the sin offering. It is generally assumed that the altar’s four horns (Exodus 27:2) symbolize divine power or divine presence. Since the worshipper cannot approach the altar as he is, the priest appeases the Lord's wrath by daubing the animal's blood on the altar. Just as the Israelites applied the blood of the lamb to the door at the time of the exodus, so now the blood on the altar allows the wrath of God to be appeased. Additionally, the four horns may symbolize the Lord’s complete protection from evil powers.
7 And the priest shall put some of the blood on the horns of the altar of fragrant incense before the LORD that is in the tent of meeting, and all the rest of the blood of the bull he shall pour out at the base of the altar of burnt offering that is at the entrance of the tent of meeting.