II Samuel 20:4

We have here Amasa's fall just as he began to rise. He was nephew to David (Sa2 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, Sa2 20:4. 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 (Sa2 20:5), 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 (Sa2 20:6, Sa2 20:7), 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, whic…

20:4-5 The king had installed Amasa in Joab’s place as commander of the armies (19:13-14). David apparently expected from Amasa the same efficiency and effectiveness as Joab had provided.