1 Kings 2:5-6

5“Moreover, you also know what Joab son of Zeruiah did to me—what he did to the two commanders of the armies of Israel, to Abner son of Ner and Amasa son of Jether, whom he killed, shedding the blood of war in peacetime, and putting the blood of war on his waistband and on his sandals on his feet.

6So act according to your wisdom, and let his gray hair not go down to Sheol in shalom.