Joab: Son of David's Sister: Defeats and Kills Abner
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2 Samuel 2:13–32
So Joab son of Zeruiah, along with the servants of David, marched out and met them by the pool of Gibeon. And the two camps took up positions on opposite sides of the pool. / Then Abner said to Joab, “Let us have the young men get up and compete before us.” “Let them get up,” Joab replied. / So they got up and were counted off—twelve for Benjamin and Ish-bosheth son of Saul, and twelve for David.
2 Samuel 3:27
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.
1 Kings 2:5
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.