Deuteronomy 3:12
And this land, which we possessed at that time, from Aroer, which is by the river Arnon, and half mount Gilead, and the cities thereof, gave I unto the Reubenites and to the Gadites. And this land, which we possessed at that time, from Aroer, which is by the river Arnon, and half mount Gilead, and the cities thereof, gave I unto the Reubenites and to the Gadites.
This allotment stands in the first of three addresses Moses gave just before his death, comprising chapters 1 to 4:40 in the fifth and last book of the Pentateuch. In that opening address he rehearses God's goodness to Israel. The recounting sets forth God's dealings with them and His deliverances on their behalf. As such, Deuteronomy repeats the law and recalls those deliverances, yet without always repeating the earlier laws word for word.
The account of the land and its conquest carries the lesson that to keep alive people wholly given over to evil would bring only corruption and harm.