I Kings 2:5-6, 31-33

“Moreover you know also what Joab the son of Zeruiah did to me, and what he did to the two commanders of the armies of Israel, to Abner the son of Ner and Amasa the son of Jether, whom he killed. And he shed the blood of war in peacetime, and put the blood of war on his belt that was around his waist, and on his sandals that were on his feet. Therefore do according to your wisdom, and do not let his gray hair go down to the grave in peace.

Then the king said to him, “Do as he has said, and strike him down and bury him, that you may take away from me and from the house of my father the innocent blood which Joab shed. So the LORD will return his blood on his head, because he struck down two men more righteous and better than he, and killed them with the sword—Abner the son of Ner, the commander of the army of Israel, and Amasa the son of Jether, the commander of the army of Judah—though my father David did not know it. Their blood shall therefore return upon the head of Joab and upon the head of his descendants forever. But upon David and his descendants, upon his house and his throne, there shall be peace forever from the LORD.”