Nehemiah 13:23-29
13:23 Also in those days I saw the men of Judah who had married women from Ashdod, Ammon, and Moab.
13:24 Half of their children spoke the language of Ashdod (or the language of one of the other peoples mentioned) and were unable to speak the language of Judah.
13:25 So I entered a complaint with them. I called down a curse on them, and I struck some of the men and pulled out their hair. I had them swear by God saying, “You will not marry off your daughters to their sons, and you will not take any of their daughters as wives for your sons or for yourselves!
13:26 Was it not because of things like these that King Solomon of Israel sinned? Among the many nations there was no king like him. He was loved by his God, and God made him king over all Israel. But the foreign wives made even him sin!
13:27 Should we then in your case hear that you do all this great evil, thereby being unfaithful to our God by marrying foreign wives?”
13:28 Now one of the sons of Joiada son of Eliashib the high priest was a son-in-law of Sanballat the Horonite. So I banished him from my sight.
13:29 Please remember them, O my God, because they have defiled the priesthood, the covenant of the priesthood, and the Levites.