Adam Clarke on 1 Kings 2:28

Tidings came to Joab - He heard that Adonijah had been slain and Abiathar banished, and probably he had heard of David's dying charge to Solomon. Fearing therefore for his personal safety, he takes refuge at the tabernacle, as claiming Divine protection, and desiring to have his case decided by God alone; or perhaps a spark of remorse is now kindled; and, knowing that he must die, he wishes to die in the house of God, as it were under the shadow, that he might receive the mercy of the Almighty.