For it was so, when Solomon was old, that his wives turned his heart after other gods; and his heart was not loyal to the LORD his God, as was the heart of his father David.
1 Kings 11:4
Surrounding context
11:3 And he had seven hundred wives, princesses, and three hundred concubines; and his wives turned away his heart.
11:4 For it was so, when Solomon was old, that his wives turned his heart after other gods; and his heart was not loyal to the LORD his God, as was the heart of his father David.
11:5 For Solomon went after Ashtoreth the goddess of the Sidonians, and after Milcom the abomination of the Ammonites.