2 Samuel 3:27-30

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

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

29May it fall upon the head of Joab and upon all his father's house, and may the house of Joab never be without one who has a discharge or who is leprous or who holds a spindle or who falls by the sword or who lacks bread!"

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