Nehemiah 13:23-27

Also in those days I saw Jews who had married women from Ashdod, Ammon, and Moab. Half the children couldn’t even speak the language of Judah; all they knew was the language of Ashdod or some other tongue. So I took those men to task, gave them a piece of my mind, even slapped some of them and jerked them by the hair. I made them swear to God: “Don’t marry your daughters to their sons; and don’t let their daughters marry your sons—and don’t you yourselves marry them! Didn’t Solomon the king of Israel sin because of women just like these? Even though there was no king quite like him, and God loved him and made him king over all Israel, foreign women were his downfall. Do you call this obedience—engaging in this extensive evil, showing yourselves faithless to God by marrying foreign wives?”