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.