2 Samuel 5:4

Overview - 2 Samuel 5
1	The tribes come to Hebron and anoint David over Israel.
4	David's age.
6	He taking Zion from the Jebusites, dwells in it.
11	Hiram sends to David.
13	Eleven sons are born to him in Jerusalem.
17	David, directed by God, smites the Philistines at Baal-perazim;
22	and again at the mulberry trees.

2 Samuel 5:4  (King James Version)
David was thirty years old when he began to reign, and he reigned forty years.