1 Kings 2:5

And thou knowest also what Joab the son of Zeruiah did to me, what he did to the two captains of the hosts of Israel, to Abner the son of Ner, and to Amasa the son of Jether, whom he slew, and shed the blood of war in peace, and put the blood of war upon his girdle that was about his loins, and upon his sandals that were on his feet.