1 Kings 11:4-6

4As Solomon grew old, his wives turned his heart after other gods, and his heart was not fully devoted to the LORD his God, as the heart of David his father had been. 5He followed Ashtoreth the goddess of the Sidonians, and Molek the detestable god of the Ammonites.

6So Solomon did evil in the eyes of the LORD ; he did not follow the LORD completely, as David his father had done.