Nehemiah 13:23-25

23In those days I also saw Jews who had married women of Ashdod, Ammon, and Moab.

24And half of their children spoke the language of Ashdod, and could not speak the language of Judah, but spoke according to the language of one or the other people.

25So I contended with them and cursed them, struck some of them and pulled out their hair, and made them swear by God, saying, “You shall not give your daughters as wives to their sons, nor take their daughters for your sons or yourselves.