Then Joab came to the king, and said, {i} What hast thou done? behold, Abner came unto thee; why is it that thou hast sent him away, and he is quite gone?

(i) Here appears the malicious mind of Joab, who would have had the king slay Abner for his private grudge.

Jamieson-Fausset-Brown Bible Commentary

24-27. Joab came to the king, and said, What hast thou done?-Joab's knowledge of Abner's wily character might have led him to doubt the sincerity of that person's proposals and to disapprove the policy of relying on his fidelity. But undoubtedly there were other reasons of a private and personal nature which made Joab displeased and alarmed by the reception given to Abner. The military talents of that general, his popularity with the army, his influence throughout the nation, rendered him a formidable rival. In the event of his overtures being carried out, the important service of bringing over all the other tribes to the king of Judah would establish so strong a claim on the gratitude of David, that his accession would inevitably raise a serious obstacle to the ambition of Joab. To these considerations was added the remembrance of the blood feud that existed between them since the death of his brother Asahel (2Sa 2:23). Determined, therefore, to get Abner out of the way, Joab feigned some reason, probably in the king's name, for recalling him, and, going out to meet him, stabbed him unawares; not within Hebron, for it was a city of refuge, but at a noted well in the neighborhood.

Matthew Henry's Concise Commentary

3:22-39 Judgments are prepared for such scorners as Abner; but Joab, in what he did, acted wickedly. David laid Abner's murder deeply to heart, and in many ways expressed his detestation of it. The guilt of blood brings a curse upon families: if men do not avenge it, God will. It is a sad thing to die like a fool, as they do that any way shorten their own days, and those who make no provision for another world. Who would be fond of power, when a man may have the name of it, and must be accountable for it, yet is hampered in the use of it? David ought to have done his duty, and then trusted God with the issue. Carnal policy spared Joab. The Son of David may long delay, but never fails to punish impenitent sinners. He who now reigns upon the throne of David, has a kingdom of a nobler kind. Whatever He doeth, is noticed by all his willing people, and is pleasing to them.