Nehemiah 13:23-25

23Also at that time, I discovered that men from Judah had married foreign women. They were women who came from Ashdod, Ammon and Moab.

24Half of their children spoke the language of Ashdod, or a language of the other foreign nations. They did not know how to speak the language of Judah.

25I was angry with them. I asked God to curse them. I hit some of the men. I pulled out the hair of some of them. I told them to make a promise in God's name. I said to them, ‘You must not let your daughters marry the sons of those foreign people. You must not let their daughters marry your sons. You yourselves must not marry foreign women either.