John Gill's Bible Commentary Ver. 4. And David took from him a thousand [chariots], and seven hundred horsemen , etc.] “Chariots” are not in the text here, it is only “horsemen”; but it is supplied from ( 1 Chronicles 18:4); where the word is expressly mentioned, and there the horsemen are said to be seven thousand as in the Septuagint version here, and in Josephus f137 ; which may be reconciled by observing, with Kimchi and Abarbinel, that here the chief officers are meant, there all the chariots and horsemen that were under their command are mentioned, which together made up that large number; or else here are meant the ranks and companies of horse David took, which were seven hundred; and these having ten in a company or rank, made seven thousand; and there the complement of soldiers in those companies and ranks are intended: and twenty thousand footmen ; the same as in ( 1 Chronicles 18:4); and so in Josephus f138 : and David houghed all the chariot [horses] ; or hamstrung them, as Joshua was ordered to do with respect to the Canaanites, ( Joshua 11:6); he did not kill them, which might seem cruel and unmerciful to the brute creatures, but hamstrung them, that they might be useless for war; and the reason of it was, that horses might not be multiplied in Israel for that purpose, that so their trust and confidence might not be placed in them; (see Deuteronomy 17:16); but reserved of them [for] an hundred chariots ; for his own use, not for war, but for grandeur; which accounts in some measure for the number of chariots and horses Solomon had, ( 1 Kings 4:26 2 Chronicles 1:14); the number of horses reserved is supposed to be four hundred, four horses being used in a chariot, which Jarchi gathers from ( 2 Chronicles 1:17).
Matthew Henry Commentary
Verses 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 tha 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. Le the line of mercy be stretched to the utmost. He smote the Syrians. I all these wars David was protected, for this in his psalms he ofte gives glory to God.
Original Hebrew וילכד3920 דוד1732 ממנו4480 אלף505 ושׁבע7651 מאות3967 פרשׁים6571 ועשׂרים6242 אלף505 אישׁ376 רגלי7273 ויעקר6131 דוד1732 את853 כל3605 הרכב7393 ויותר3498 ממנו4480 מאה3967 רכב׃7393