1 Kings 11:42 KJV

And the time that Solomon reigned in Jerusalem over all Israel was forty years.
1 Kings 11:42, King James Version

In context

41 And the rest of the acts of Solomon, and all that he did, and his wisdom, are they not written in the book of the acts of Solomon?

42 And the time that Solomon reigned in Jerusalem over all Israel was forty years.

43 And Solomon slept with his fathers, and was buried in the city of David his father: and Rehoboam his son reigned in his stead.