1 Kings 11:4-6

For when Solomon was old, his wives turned his heart away after other gods; and his heart was not completely devoted to the LORD his God, as was the heart of his father David. For Solomon went after Ashtoreth, the [fertility] goddess of the Sidonians, and after Milcom the horror (detestable idol) of the Ammonites. [1 Kin 9:6-9] Solomon did evil [things] in the sight of the LORD, and did not follow the LORD fully, as his father David had done.