2 Samuel 3:8

Then was Abner very wroth. This extreme indignation on Abner's part is not easy to understand; for he could scarcely have expected Ishbosheth to endure quietly what at least was a great insult. But probably the question, Wherefore hast thou gone in unto my father's concubine? does not mean a mild expostulation on the king's part, but the purpose to degrade Abner and strip him of his office. Probably after the defeat by Joab at Gibeon, the army was less satisfied with its leader, and his detractors may gladly have encouraged the king to use this opportunity for bringing Abner down to his proper place. Weak kings often try to play the strong man; but the attempt here only drove the imperious soldier to put the matter to the proof, and show that the strength was his. We know that David groaned all his life through under Joab's iron will, and, though he tried, yet that he never succeeded in throwing off the yoke. But Joab never behaved unfaithfully to his sovereign as Abner did here, and his crimes were deeds of violence committed in David's cause. Am I a dog's head, which against Judah, etc.? The words literally are, Am I a dog's head that is for Judah? and are rightly rendered in the Revised Version, Am I a dog's head that belongeth to Judah? Am I at once worthless and a traitor, a thing of no account, and on the side of thy enemies? In the words that follow he protests, not so much his innocence as his great deserts. This day —that is, at this very time— I am showing kindness unto the house of Saul … and this day thou wouldest visit upon me— that is, punish me for— the fault about this woman. I make and maintain thee as king, and thou wouldst play the king upon me, the kingmaker!