Joab: Son of David's Sister: Defeats and Kills Abner

So Joab son of Zeruiah and the servants of David marched out and met them by the pool of Gibeon. And the two groups took up positions on opposite sides of the pool. …

When Abner returned to Hebron, Joab pulled him aside into the gateway, as if to speak to him privately, and there Joab stabbed him in the stomach. So Abner died on account of the blood of Joab’s brother Asahel.

Moreover, you know what Joab son of Zeruiah did to me—what he did to Abner son of Ner and Amasa son of Jether, the two commanders of the armies of Israel. He killed them in peacetime to avenge the blood of war. He stained with the blood of war the belt around his waist and the sandals on his feet.