Leviticus 4:18
And he shall put some of the blood upon the horns of the altar which is before the Lord, that is in the tabernacle of the congregation, and shall pour out all the blood at the bottom of the altar of the burnt offering, which is at the door of the tabernacle of the congregation.
Cross-reference
Leviticus 4:7 gives the same sin offering instructions for the anointed priest — identical blood application to the incense altar horns and base.
Leviticus 4:25 applies blood to the burnt offering altar's horns instead of the incense altar — a contrast based on the offerer's status.
Leviticus 8:15 records Moses putting blood on the horns and base of the burnt offering altar to consecrate it — a parallel action with a different purpose.
Leviticus 9:9 shows Aaron performing this exact sin offering ritual: blood on the horns and poured at the base.
Leviticus 16:18 on the Day of Atonement has blood applied to the incense altar's horns — the same action for a different annual atonement.
Leviticus 5:9 prescribes sprinkling blood on the side of the altar rather than on horns — a different method for a less valuable offering.
Exodus 29:12 shows a parallel ritual: blood on the horns and base of the altar during priestly consecration, though on the burnt offering altar.
Jeremiah 17:1 uses the horns of the altar to symbolize indelible sin, echoing the blood application in this verse.