2 Samuel 3:27-30

27Now when Abner had returned to Hebron, Joab took him aside in the gate to speak with him privately, and there stabbed him in the stomach, so that he died for the blood of Asahel his brother.

28Afterward, when David heard it, he said, “My kingdom and I are guiltless before the Lord forever of the blood of Abner the son of Ner.

29Let it rest on the head of Joab and on all his father’s house; and let there never fail to be in the house of Joab one who has a discharge or is a leper, who leans on a staff or falls by the sword, or who lacks bread.”

30So Joab and Abishai his brother killed Abner, because he had killed their brother Asahel at Gibeon in the battle.