So Joab and Abishai his brother slew Abner,.... For though it was only Joab that gave him the thrust of which he died, Abishai was in the secret, and was consenting and advising to his death, and so an accessory to it; and might be present, ready to assist in it, if occasion required; and so Josephus (k) expressly says, that Abishai his brother was with him when he drew his sword, and smote him:

because he had slain their brother Asahel at Gibeon in the battle: which was no just reason at all; his blood was shed in war, this in peace, in cold blood, and under the guise of friendship; that was shed with reluctance, and after fair warning, and in defence of himself; but this wilfully in Joab, unawares to Abner, and in great deceit and hypocrisy; see 1 Kings 2:5.

(k) Ut supra. (Antiqu. l. 7. c. 1. sect. 6.)

So Joab and {l} Abishai his brother slew Abner, because he had slain their brother Asahel at Gibeon in the battle.

(l) Abishai is said to slay him with Joab, because he consented to the murder.

3:30 Abishai - For though Joab only committed the murder, yet Abishai was guilty of it, because it was done with his consent, and counsel, and approbation. In battle - Which he did for his own necessary defence; and therefore it was no justification of this treacherous murder.

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.