19 and thou hast come near over-against the sons of Ammon, thou dost not distress them, nor stir up thyself against them, for I do not give 'any' of the land of the sons of Ammon to thee 'for' a possession; for to the sons of Lot I have given it 'for' a possession. 20 'A land of Rephaim it is reckoned, even it; Rephaim dwelt in it formerly, and the Ammonites call them Zamzummim; 21 a people great, and numerous, and tall, as the Anakim, and Jehovah destroyeth them before them, and they dispossess them, and dwell in their stead,
Matthew Henry's Commentary on Deuteronomy 2:19-21
Commentary on Deuteronomy 2:8-23
(Read Deuteronomy 2:8-23)
We have the origin of the Moabites, Edomites, and Ammonites. Moses also gives an instance older than any of these; the Caphtorims drove the Avims out of their country. These revolutions show what uncertain things wordly possessions are. It was so of old, and ever will be so. Families decline, and from them estates are transferred to families that increase; so little continuance is there in these things. This is recorded to encourage the children of Israel. If the providence of God has done this for Moabites and Ammonites, much more would his promise do it for Israel, his peculiar people. Cautions are given not to meddle with Moabites and Ammonites. Even wicked men must not be wronged. God gives and preserves outward blessings to wicked men; these are not the best things, he has better in store for his own children.