Nehemiah 13:23-25

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

24As for their children, half spoke in the language of Ashdod, and none of them knew how to speak [Hebrew] the language of Judah, but only the language of his own people.

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