Leviticus 8:15

Moses took the blood, &c., and purified the altar This ceremony of touching the altar with blood emphatically signified that all the services which they offered to God partook of their impurity, and that the very altar which consecrated their oblations was defiled by their unhallowed touch. But the sprinkling it with the blood of the victim, which, by divine appointment, was substituted and accepted instead of the forfeited life of the sinner, made room for repentance, the removal of guilt, and purification; on which account the altar is said to be purified and sanctified by this action.