Jamieson-Fausset-Brown on 2 Samuel 24:5
they passed over Jordan--This census was taken first in the eastern parts of the Hebrew kingdom; and it would seem that Joab was accompanied by a military force, either to aid in this troublesome work, or to overawe the people who might display reluctance or opposition.
the river of Gad--"Wady" would be a better term. It extends over a course estimated at about sixty miles, which, though in summer almost constantly dry, exhibits very evident traces of being swept over by an impetuous torrent in winter (see Deu 2:36).
Adam Clarke on 2 Samuel 24:5
And pitched in Aroer - This was beyond Jordan, on the river Arnon, in the tribe of Gad: hence it appears, says Calmet, that they began their census with the most eastern parts of the country beyond Jordan.
John Gill on 2 Samuel 24:5
And they passed over Jordan,.... To take the number of the tribes of Reuben and Gad and the half tribe of Manasseh first:
and pitched in Aroer; for it seems that Joab and the captains had the army with them, and the several captains under their command, partly to assist in numbering the people, and partly to keep them in awe, lest they should oppose them, not knowing what was the design of all this Aroer was a city given to the tribe of Gad, and rebuilt by them, Numbers 32:34,
on the right side of the city; that is, of Aroer, the south side of it, as the Targum, did Joab and his army pitch:
that lieth in the midst of the river of Gad; which was the river Arnon, so called now from the trib…
Read the whole note in the consoleKeil & Delitzsch on 2 Samuel 24:1-9
"Again the anger of Jehovah was kindled against Israel; and He moved David against them, saying, Go, number Israel and Judah." לחרות ... ויּסף points back to the manifestation of the wrath of God, which Israel had experienced in the three years' famine (2 Samuel 21). Just as that plague had burst upon the land on account of the guilt which rested upon the people, so the kindling of the wrath of God against Israel a second time also presupposes guilt on the part of the nation; and as this is not expressly pointed out, we may seek for it generally in the rebellions of Absalom and Sheba against the divinely established government of David. The subject to "moved" is Jehovah, and the words "again…