Nehemiah 9:2

And the seed of Israel, the Jews of pure blood, separated themselves from all strangers, foreigners who had become mixed with the Jews by marriage, and stood and confessed their sins and the iniquities of their fathers, principally in contracting such marriages as were expressly forbidden by God; for the reforms of Ezra had not lasted, the people having once more taken up, not only commercial intercourse, but also the dangerous custom of intermarriages with the heathen nations.