1 Kings 11:2

11:2 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.

Deuteronomy 7:4

7:4 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.

Deuteronomy 17:17

17:17 Furthermore, he must not marry many wives lest his affections turn aside, and he must not accumulate much silver and gold.

Nehemiah 13:26-27

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?”