Deuteronomy 23:3-4

23:3 An Ammonite or Moabite may not enter the assembly of the Lord; to the tenth generation none of their descendants shall ever do so, 23:4 for they did not meet you with food and water on the way as you came from Egypt, and furthermore, they hired Balaam son of Beor of Pethor in Aram Naharaim to curse you.