Nehemiah 13:22-26

And I ordered the Levites that they were to purify themselves and come as gatekeepers to sanctify the Sabbath day. For this also remember me, my God, and have compassion on me according to the greatness of Your mercy. Mixed Marriages Forbidden

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

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

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

Did Solomon the king of Israel not sin regarding these things? Yet among the many nations there was no king like him, and he was loved by his God, and God made him king over all Israel; yet the foreign women caused even him to sin.