2 Samuel 5:3-5

All the leaders of Israel met with King David at Hebron, and the king made a treaty with them in the presence of GOD. And so they anointed David king over Israel. * * * David was thirty years old when he became king, and ruled for forty years. In Hebron he ruled Judah for seven and a half years. In Jerusalem he ruled all Israel and Judah for thirty-three years.