Nehemiah 13:1-3

On that day the Book of Moses was read aloud in the hearing of the people and there it was found written that no Ammonite or Moabite should ever be admitted into the assembly of God, because they had not met the Israelites with food and water but had hired Balaam to call a curse down on them. (Our God, however, turned the curse into a blessing.) When the people heard this law, they excluded from Israel all who were of foreign descent.