Deuteronomy 23:2-4

New Century Version

² No one born to parents who were forbidden by law to marry may come into the meeting to worship the Lord. The descendants for ten generations may not come in either.

³ No Ammonite or Moabite may come into the meeting to worship the Lord, and none of their descendants for ten generations may come in. ⁴ This is because the Ammonites and Moabites did not give you bread and water when you came out of Egypt. And they hired Balaam son of Beor, from Pethor in Northwest Mesopotamia, to put a curse on you.