Genesis 19:37-38

19:37 The older daughter gave birth to a son and named him Moab. He is the ancestor of the Moabites of today. 19:38 The younger daughter also gave birth to a son and named him Ben-Ammi. He is the ancestor of the Ammonites of today.

Deuteronomy 2:9

2:9 Then the Lord said to me, “Do not harass Moab and provoke them to war, for I will not give you any of their land as your territory. This is because I have given Ar to the descendants of Lot as their possession.