1 Kings 2:28

Then tidings came to Joab Concerning Adonijah's death, and Abiathar's deposition. And Joab fled unto the tabernacle of the Lord This makes it appear that Joab had had a hand in the counsel mentioned 1 Kings 2:22, as Solomon suspected. And caught hold on the horns of the altar It appears from this and some other instances, that it was now become a custom among the Israelites, though by no divine law, to flee to the altar of the Lord, as to an asylum; however, by Solomon's treatment of Joab on this occasion, it appears, that this privilege was only allowed for some misdemeanours, and not for capital offences, especially murder. And Solomon (1Ki 2:31) showed that the altar had better be stained with the blood of a murderer, than be polluted with his touch, in seeking an asylum from it, and thereby escaping the punishment which the divine laws required to be inflicted on him.