1 Kings 2:5-6

2:5 “You know what Joab son of Zeruiah did to me – how he murdered two commanders of the Israelite armies, Abner son of Ner and Amasa son of Jether. During peacetime he struck them down like he would in battle; when he shed their blood as if in battle, he stained his own belt and the sandals on his feet. 2:6 Do to him what you think is appropriate, but don’t let him live long and die a peaceful death.

1 Kings 2:31-32

2:31 The king told him, “Do as he said! Strike him down and bury him. Take away from me and from my father’s family the guilt of Joab’s murderous, bloody deeds. 2:32 May the Lord punish him for the blood he shed; behind my father David’s back he struck down and murdered with the sword two men who were more innocent and morally upright than he – Abner son of Ner, commander of Israel’s army, and Amasa son of Jether, commander of Judah’s army.