Also in those days I saw the men of Judah who had married women from Ashdod, Ammon, and Moab. 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. 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! read more.
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! Should we then in your case hear that you do all this great evil, thereby being unfaithful to our God by marrying foreign wives?"

King Solomon fell in love with many foreign women (besides Pharaoh's daughter), including Moabites, Ammonites, Edomites, Sidonians, and Hittites. They came from nations about which the Lord had warned the Israelites, "You must not establish friendly relations with them! If you do, they will surely shift your allegiance to their gods." But Solomon was irresistibly attracted to them. He had 700 royal wives and 300 concubines; his wives had a powerful influence over him. read more.
When Solomon became old, his wives shifted his allegiance to other gods; he was not wholeheartedly devoted to the Lord his God, as his father David had been. Solomon worshiped the Sidonian goddess Astarte and the detestable Ammonite god Milcom. Solomon did evil in the Lord's sight; he did not remain loyal to the Lord, like his father David had. Furthermore, on the hill east of Jerusalem Solomon built a high place for the detestable Moabite god Chemosh and for the detestable Ammonite god Milcom. He built high places for all his foreign wives so they could burn incense and make sacrifices to their gods.

"Obey what I am commanding you this day. I am going to drive out before you the Amorite, the Canaanite, the Hittite, the Perizzite, the Hivite, and the Jebusite. Be careful not to make a covenant with the inhabitants of the land where you are going, lest it become a snare among you. Rather you must destroy their altars, smash their images, and cut down their Asherah poles. read more.
For you must not worship any other god, for the Lord, whose name is Jealous, is a jealous God. Be careful not to make a covenant with the inhabitants of the land, for when they prostitute themselves to their gods and sacrifice to their gods, and someone invites you, you will eat from his sacrifice; and you then take his daughters for your sons, and when his daughters prostitute themselves to their gods, they will make your sons prostitute themselves to their gods as well.

When the Lord your God brings you to the land that you are going to occupy and forces out many nations before you -- Hittites, Girgashites, Amorites, Canaanites, Perizzites, Hivites, and Jebusites, seven nations more numerous and powerful than you -- and he delivers them over to you and you attack them, you must utterly annihilate them. Make no treaty with them and show them no mercy! You must not intermarry with them. Do not give your daughters to their sons or take their daughters for your sons, read more.
for they will turn your sons away from me to worship other gods. Then the anger of the Lord will erupt against you and he will quickly destroy you.

Judah has become disloyal, and unspeakable sins have been committed in Israel and Jerusalem. For Judah has profaned the holy things that the Lord loves and has turned to a foreign god! May the Lord cut off from the community of Jacob every last person who does this, as well as the person who presents improper offerings to the Lord who rules over all! You also do this: You cover the altar of the Lord with tears as you weep and groan, because he no longer pays any attention to the offering nor accepts it favorably from you.