Then Solomon was told, “Behold, Adonijah fears King Solomon, for he has caught hold of the horns on the altar, saying ‘Let King Solomon swear to me today that he will not slay his servant with the sword.’ ”
Then word came to Joab, for Joab had followed Adonijah, though he did not support Absalom. And Joab fled to the tabernacle of the Lord and caught hold of the horns of the altar.
Aaron must make atonement on its horns once a year with the blood of the sin offering of atonement. Once a year he must make atonement on it throughout your generations. It is most holy to the Lord.