Nehemiah 13:23-28 New Revised Standard Version (NRSV)
Mixed Marriages Condemned
23 In those days also I saw Jews who had married women of Ashdod, Ammon, and Moab; 24 and half of their children spoke the language of Ashdod, and they could not speak the language of Judah, but spoke the language of various peoples. 25 And I contended with them and cursed them and beat some of them and pulled out their hair; and I made them take an oath in the name of God, saying, “You shall not give your daughters to their sons, or take their daughters for your sons or for yourselves. 26 Did not King Solomon of Israel sin on account of such women? Among the many nations there was no king like him, and he was beloved by his God, and God made him king over all Israel; nevertheless, foreign women made even him to sin. 27 Shall we then listen to you and do all this great evil and act treacherously against our God by marrying foreign women?”
28 And one of the sons of Jehoiada, son of the high priest Eliashib, was the son-in-law of Sanballat the Horonite; I chased him away from me.