Rashbam on Deuteronomy
כי לבני לוט, on account of his having been Avraham’s nephew.
Chizkuni
וקרבת מול בני עמון, “when you come near to being opposite the Bney Ammon;” actually they did not get to the boundary of the Bney Ammon, as their lands were to the east of both the kingdoms of Sichon and Og, king of Bashan.