Nehemiah 13:21-25

Then I warned them and said to them, “Why do you spend the night in front of the wall? If you do so again, I will use force against you.” From that time on they did not come on the Sabbath.

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.