2 Samuel 24:5 - Matthew Poole's English Annotations on the Holy Bible

They passed over Jordan; they began their computation in the eastern part of David's dominions, which were beyond Jordan. Pitched, or encamped. For Joab carried with them divers of his commanders, and others; partly, for his honour, and, the credit of the work; partly, to assist him in that troublesome work; and partly, to overcome the people, in case they should oppose it as sinful or burdensome, or savouring of some evil design which David might have upon them. Of the river of Gad, i. e. of the river which lay in the tribe of Gad, or upon the borders of Gad and Reuben, which was called Arnon, Deuteronomy 2:36. Toward Jazer, or, near Jazer, which also was upon the river Arnon.