And when the children of Ammon saw that the Syrians were fled, they likewise fled before Abishai his brother, and entered into the city. Then Joab came to Jerusalem.

Matthew Henry's Concise Commentary

19:1-19 David's wars. - The history is here repeated which we read 2Sa 10. The only safety of sinners consists in submitting to the Lord, seeking peace with him, and becoming his servants. Let us assist each other in a good cause; but let us fear lest, while made instruments of good to others, we should come short of salvation, through unbelief and sin.

Matthew Henry's Whole Bible Commentary

Verses 6-19

We may see here, 1. How the hearts of sinners that are marked for ruin are hardened to their destruction. The children of Ammon saw that they had made themselves odious to David (v. 6), and then it would have been their wisdom to desire conditions of peace, to humble themselves and offer any satisfaction for the injury they had done him, the rather because they had made themselves not only odious to David, but obnoxious to the justice of God, who is King of nations, and will assert the injured rights and maintain the violated laws of nations. But, instead of this, they prepared for war, and so brought upon themselves, by David's hand, those desolations which he never intended them. 2. How the courage of brave men is heightened and invigorated by difficulties. When Joab saw that the battle was set against him before and behind (v. 10), instead of meditating a retreat, he doubled his resolution; and, though he could not double, he divided his army, and not only spoke, but acted, like a gallant man, that had great presence of mind when he saw himself surrounded. He engaged with his brother for mutual assistance (v. 12), excited himself and the rest of the officers to act vigorously in their respective posts, with an eye to God's glory and their country's good, not to any honour and advantage of their own, and then left the issue to God: Let the Lord do that which is right in his sight. 3. How vain the greatest art and strength are against justice and equity. The Ammonites did their utmost to make the best of their position: they brought as good a force into the field, and disposed it with as much policy as possible; yet, having a bad cause, and acting in defence of wrong, it would not do; they were put to the worst. Right will prevail and triumph at last. 4. To how little purpose it is for those to rally again, and reinforce themselves, that have not God on their side. The Syrians, though in no way concerned in the merits of the cause, but serving only as mercenaries to the Ammonites, when they were beaten, thought themselves concerned to retrieve their honour, and therefore called in the assistance of the Syrians on the other side Euphrates; but to no purpose, for still they fled before Israel (v. 18); they lost 7000 men, who are said to be the men of 700 chariots, 2 Sa. 10:18. For, as now in a man of war for sea-service they allot ten men to a gun, so then, in land-service, ten men to a chariot. 5. those who have meddled with strife that belongs not to them, and have found that they meddled to their own heart, do well to learn wit at length and meddle no further. The Syrians, finding that Israel was the conquering side, not only broke off their alliance with the Ammonites and would help them no more (v. 19), but made peace with David and became his servants. Let those who have in vain stood it out against God be thus wise for themselves, and agree with him quickly, while they are in the way. Let them become his servants; for they cannot but see themselves undone if they be his enemies.