Deuteronomy 23:3-6

No Ammonite or Moabite or any of their descendants may enter the assembly of the LORD, not even in the tenth generation. For they did not come to meet you with bread and water on your way when you came out of Egypt, and they hired Balaam son of Beor from Pethor in Aram Naharaim to pronounce a curse on you. However, the LORD your God would not listen to Balaam but turned the curse into a blessing for you, because the LORD your God loves you. Do not seek a treaty of friendship with them as long as you live.