1 Chronicles 29:27

For forty years he was ruling as king over Israel, seven years in Hebron and thirty-three years in Jerusalem.

2 Samuel 5:4-5

David was thirty years old when he became king, and he was king for forty years,

1 Kings 2:11

David was king over Israel for forty years: for seven years he was king in Hebron and for thirty-three years in Jerusalem.

1 Chronicles 3:4

He had six sons in Hebron; he was ruling there for seven years and six months, and in Jerusalem for thirty-three years.

Treasury of Scripture Knowledge

Summary

And the time that he reigned over Israel was forty years; seven years reigned he in Hebron, and thirty and three years reigned he in Jerusalem.

Bible References

Forty years

1 Chronicles 3:4
He had six sons in Hebron; he was ruling there for seven years and six months, and in Jerusalem for thirty-three years.
2 Samuel 5:4
David was thirty years old when he became king, and he was king for forty years,
1 Kings 2:11
David was king over Israel for forty years: for seven years he was king in Hebron and for thirty-three years in Jerusalem.

Basic English, produced by Mr C. K. Ogden of the Orthological Institute - public domain