1 Kings 2:4-6

4that the Lord may establish his word that he spoke concerning me, saying, 'If your sons pay close attention to their way, to walk before me in faithfulness with all their heart and with all their soul, you shall not lack a man on the throne of Israel.'

5"Moreover, you also know what Joab the son of Zeruiah did to me, how he dealt with the two commanders of the armies of Israel, Abner the son of Ner, and Amasa the son of Jether, whom he killed, avenging in time of peace for blood that had been shed in war, and putting the blood of war on the belt around his waist and on the sandals on his feet.

6Act therefore according to your wisdom, but do not let his gray head go down to Sheol in peace.