8:2 And he smote Moab, and measured them with a line, casting them down to the ground; even with {b} two lines measured he to put to death, and with one full line to keep alive. And [so] the Moabites became David's servants, [and] brought gifts.

(b) He slew two parts as it pleased him, and reserved the third.

8:2 Moab - For although the king of Moab, out of hatred to Saul, gave protection to his parents, 1Sam 22:3,4, yet the Moabites were perpetual and sworn enemies to the Israelites, who therefore were forbidden to admit them into the congregation of the Lord. And though God commanded them in their march to Canaan, to spare the Moabites, yet afterwards they proved fierce enemies to God and his people, and thereby provoked God to alter his carriage towards them. Measured them - That is, having conquered the land, he made an estimate of it, and distributed the towns and people into three parts. Casting down - Overthrowing their towns, and utterly destroying their people in manner following. And now that prophecy, Numb 24:17, was accomplished.

8:1-8. David subdued the Philistines. They had long been troublesome to Israel. And after the long and frequent struggles the saints have with the powers of darkness, like Israel with the Philistines, the Son of David shall tread them all under foot, and make the saints more than conquerors. He smote the Moabites, and made them tributaries to Israel. Two parts he destroyed, the third part he spared. The line that was to keep alive, though it was but one, is ordered to be a full line. Let the line of mercy be stretched to the utmost. He smote the Syrians. In all these wars David was protected, for this in his psalms he often gives glory to God.