1 Kings 11:4-8

For when Solomon was old, his wives turned his heart away to follow other gods; and his heart was not wholly devoted to the Lord his God, as the heart of his father David had been.

For Solomon became a follower of Ashtoreth the goddess of the Sidonians, and of Milcom the abhorrent idol of the Ammonites.

So Solomon did what was evil in the sight of the Lord, and did not follow the Lord fully, as his father David had done.

Then Solomon built a high place for Chemosh, the abhorrent idol of Moab, on the mountain that is east of Jerusalem, and for Molech, the abhorrent idol of the sons of Ammon.

He also did the same for all his foreign wives, who burned incense and sacrificed to their gods.