2 Samuel 3:27

And when Abner was returned to Hebron, undoubtedly under the impression that David had some further instructions for him, Joab took him aside in the gate to speak with him quietly, in secret, in private, his attendants therefore retiring, and smote him there under the fifth rib, in the abdomen, that he died, for the blood of Asahel, his brother, for whom Joab considered himself an avenger. Joab's deed was murder and cast false suspicions on David; his real ground for committing it was false ambition and envy, for he feared that lie would be superseded by the more renowned Abner.