2 Samuel 3:24

What hast thou done? — Joab’s somewhat rough remonstrance with David may have been supported by an honest suspicion of Abner, for which there was some ground in Abner’s long opposition to the known Divine will and his present revolt from Ish-bosheth; but there was also a personal enmity, due partly to the fear of being himself supplanted by an older and famous warrior, and partly to the desire to revenge the death of his brother Asahel. Joab seeks to poison David’s mind against Abner, that he may better carry out his revenge.