1 Kings 2:5-6, 31-33

Now you also know what Joab the son of Zeruiah [my sister] did to me, and what he did to the two commanders of the armies of Israel, to Abner the son of Ner and to Amasa the son of Jether, [both of] whom he murdered; avenging the blood of war in [a time of] peace. And he put the [innocent] blood of war [of Abner and Amasa] on his belt that was around his waist, and on his sandals on his feet. So act in accordance with your wisdom, but do not let his gray head go down to Sheol (the place of the dead) in peace.

The king said to him, “Do as he has said. Strike him down and bury him, so that you may remove from me and from my father’s house the innocent blood which Joab shed. The LORD will return his bloody deeds upon his own head, because he struck down two men more righteous and honorable than he and killed them with the sword, without my father David knowing: Abner the son of Ner, commander of the army of Israel, and Amasa the son of Jether, commander of the army of Judah. So shall their blood return on the head of Joab and the heads of his descendants forever. But for David, his descendants, his house, and his throne, may there be peace from the LORD forever.”