1 Kings 2:5-6

5“Now you yourself know what Joab son of Zeruiah did to me—what he did to the two commanders of Israel’s armies, Abner son of Ner and Amasa son of Jether. He killed them, shedding their blood in peacetime as if in battle, and with that blood he stained the belt around his waist and the sandals on his feet. 6Deal with him according to your wisdom, but do not let his gray head go down to the grave in peace.