Nehemiah 13:1-3

On that day they read in the book of Moses in the audience of the people; and therein was found written, that the Ammonite and the Moabite should not come into the congregation of God for ever; because they met not the children of Israel with bread and with water, but hired Balaam against them, that he should curse them: howbeit our God turned the curse into a blessing. Now it came to pass, when they had heard the law, that they separated from Israel all the mixed multitude.