Kings III 11:4

4 And it came to pass in the time of the old age of Solomon, that his heart was not perfect with the Lord his God, as the heart of David his father.

Kings III 11:4 In-Context

2 of the nations concerning whom the Lord forbade the children of Israel, , Ye shall not go in to them, and they shall not come in to you, lest they turn away your hearts after their idols: Solomon clave to these in love.
4 And it came to pass in the time of the old age of Solomon, that his heart was not perfect with the Lord his God, as the heart of David his father.
5 and to Astarte the abomination of the Sidonians.
6 And thus he acted towards all his strange wives, who burnt incense and sacrificed to their idols.

The Brenton translation of the Septuagint is in the public domain.