1 Kings 11:4-6

For it came to pass, when Solomon was old, that his wives turned away his heart after other gods: and his heart was not perfect with the LORD his God, as was the heart of David his father.

For Solomon went after Ashtoreth the goddess of the Zidonians, and after Milcom the abomination of the Ammonites.

And Solomon did evil in the sight of the LORD, and went not fully after the LORD, as did David his father.