What did the high priest do with the two animal bloods on the Day of Atonement?
On the Day of Atonement, the high priest first entered with the blood of one animal and sprinkled it behind the curtain on the mercy seat for his own sin. He then took the blood of a second animal behind the veil and sprinkled it on the mercy seat, covering the sins of the nation.
Les explains from Hebrews chapter 9 that Paul is rehearsing the Day of Atonement. The high priest would go in first with the blood of an animal and sprinkle it behind the curtain on the Holy of Holies, or on the Ark of the Covenant, the mercy seat, for his own sin. Then he would take the blood of the second animal, carry it behind the veil, and sprinkle it on the mercy seat in the Holy of Holies, taking care of the sins of the nation. Les then contrasts this with Christ, the high priest, who entered a greater and more perfect tabernacle not made with hands—heaven itself—not by the blood of goats and calves but by His own blood, once for all, obtaining eternal redemption.