John Gills Exposition of the Bible Commentary - 2 Samuel 3:30
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 F11 Ut supra. (Antiqu. l. 7. c. 1. sect. 6.) 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... read more
Matthew Henry's Complete Commentary - 2 Samuel 3:22-39
We have here an account of the murder of Abner by Joab, and David's deep resentment of it. I. Joab very insolently fell foul upon David for treating with Abner. He happened to be abroad upon service when Abner was with David, pursuing a troop, either of Philistines or of Saul's party; but, upon his return, he was informed that Abner was just gone (2 Sam. 3:22, 23), and that a great many kind things had passed between David and him. He had all the reason in the world to be satisfied of David's... read more