We have here Amasa’s fall just as he began to rise. He was nephew to David (ch. 17:25), had been Absalom’s general and commander-in-chief of his rebellious army, but, that being routed, he came over into David’s interest, upon a promise that he should be general of his forces instead of Joab. Sheba’s rebellion gives David an occasion to fulfil his promise sooner than he could wish, but Joab’s envy and emulation rendered its fulfillment of ill consequence both to him and David.

I. Amasa has a commission to raise forces for the suppressing of Sheba’s rebellion, and is ordered to raise them with all possible expedition, v. 4. It seems, the men of Judah, though forward to attend the king’s triumphs, were backward enough to fight his battles; else, when they were all in a body attending him to Jerusalem, they might immediately have pursued Sheba, and have crushed that cockatrice in the egg. But most love a loyalty, as well as a religion, that is cheap and easy. Many boast of their being akin to Christ that yet are very loth to venture for him. Amasa is sent to assemble the men of Judah within three days; but he finds them so backward and unready that he cannot do it within the time appointed (v. 5), though the promotion of Amasa, who had been their general under Absalom, was very obliging to them, and a proof of the clemency of David’s government.

II. Upon Amasa’s delay, Abishai, the brother of Joab, is ordered to take the guards and standing forces, and with them to pursue Sheba (v. 6, 7), for nothing could be of more dangerous consequence than to give him time. David gives these orders to Abishai, because he resolves to mortify Joab, and degrade him, not so much, I doubt, for the blood of Abner, which he had shed basely, as for the blood of Absalom, which he had shed justly and honourably. "Now (says bishop Hall) Joab smarteth for a loyal disobedience. How slippery are the stations of earthly honours and subject to continual mutability! Happy are those who are in favour with him in whom there is no shadow of change." Joab, without orders, though in disgrace, goes along with his brother, knowing he might be serviceable to the public, or perhaps now meditating the removal of his rival.

III. Joab, near Gibeon, meets with Amasa, and barbarously murders him, v. 8–10. It should seem, the great stone in Gibeon was the place appointed for the general rendezvous. There the rivals met; and Amasa, relying upon his commission, went before, as general both of the new-raised forces which he had got together, and of the veteran troops which Abishai had brought in; but Joab there took an opportunity to kill him with his own hand; and, 1. He did it subtilely, and with contrivance, and not upon a sudden provocation. He girded his coat about him, that it might not hang in his way, and girded his belt upon his coat, that his sword might be the readier to his hand; he also put his sword in a sheath too big for it, that, whenever he pleased, it might, upon a little shake, fall out, as if it fell by accident, and so he might take it into his hand, unsuspected, as if he were going to return it into the scabbard, when he designed to sheath it in the bowels of Amasa. The more there is of plot in a sin the worse it is. 2. He did it treacherously, and under pretence of friendship, that Amasa might not be upon his guard. He called him brother, for they were own cousins, enquired of his welfare (Art thou in health?) and took him by the beard, as one he was free with, to kiss him, while with the drawn sword in his other hand he was aiming at his heart. Was this done like a gentleman, like a soldier, like a general? No, but like a villain, like a base coward. Just thus he slew Abner, and went unpunished for it, which encouraged him to do the like again. 3. He did it impudently, not in a corner, but at the head of his troops, and in their sight, as one that was neither ashamed nor afraid to do it, that was so hardened in blood and murders that he could neither blush nor tremble. 4. He did it at one blow, gave the fatal push with a good-will, as we say, so that he needed not strike him again; with such a strong and steady hand he gave this one stroke that it was fatal. 5. He did it in contempt and defiance of David and the commission he had given to Amasa; for that commission was the only ground of his quarrel with him, so that David was struck at through the side of Amasa, and was, in effect, told to his face that Joab would be general, in spite of him. 6. He did it very unseasonably, when they were going against a common enemy and were concerned to be unanimous. This ill-timed quarrel might have scattered their forces, or engaged them one against another, and so have made them all an easy prey to Sheba. So contentedly could Joab sacrifice the interest both of king and kingdom to his personal revenge.

IV. Joab immediately resumes his general’s place, and takes care to lead the army on in pursuit of Sheba, that, if possible, he might prevent any prejudice to the common cause by what he had done. 1. He leaves one of his men to make proclamation to the forces that were coming up that they were still engaged in David’s cause, but under Joab’s command, v. 11. He knew what an interest he had in the soldiery, and how many favoured him rather than Amasa, who had been a traitor, was now a turn-coat, and had never been successful; on this he boldly relied, and called them all to follow him. What man of Judah would not be for his old king and his old general? But one would wonder with what face a murderer could pursue a traitor; and how, under such a heavy load of guilt, he had courage to enter upon danger. Surely his conscience was seared with a hot iron. 2. care is taken to remove the dead body out of the way, because at that they made a stand (as ch. 2:23), and to cover it with a cloth, v. 12, 13. Wicked men think themselves safe in their wickedness if they can but conceal it from the eye of the world: if it be hidden, it is with them as if it were never done. But the covering of blood with a cloth cannot stop its cry in God’s ear for vengeance, or make it the less loud. However, since this was no time to arraign Joab for what he had done, and the common safety called for expedition, it was prudent to remove that which retarded the march of the army; and then they all went on after Joab, while David, who no doubt had notice soon brought him of this tragedy, could not but reflect upon it with regret that he had not formerly done justice upon Joab for the death of Abner, and that he now had exposed Amasa by preferring him. And perhaps his conscience reminded him of his employing Joab in the murder of Uriah, which had helped to harden him in cruelty.