while they were in the valley across the Jordan facing Beth-peor in the land of Sihon king of the Amorites, who lived in Heshbon and was defeated by Moses and the Israelites after they had come out of Egypt.
Here is, 1. The nomination of the cities of refuge on that side Jordan where Israel now lay encamped. Three cities were appointed for that purpose, one in the lot of Reuben, another in that of Gad, and another in that of the half tribe of Manasseh, Deu 4:41-43.
Commenting on Deuteronomy 4:41-49
And they possessed his land, and the land of Og king of Bashan,.... Seized upon them, and took them as their own, and divided them for an inheritance among two of their tribes and half another: two kings of the Amorites; which is more than once observed, that it might be taken notice of that these were of the nations of the Canaanites Israel were...
Beth-peor--that is, "house" or "temple of Peor." It is probable that a temple of this Moabite idol stood in full view of the Hebrew camp, while Moses was urging the exclusive claims of God to their worship, and this allusion would be very significant if it were the temple where so many of the Israelites had grievously offended.