3 And all the elders of Israel come unto the king, to Hebron, and king David maketh with them a covenant in Hebron before Jehovah, and they anoint David for king over Israel. 4 A son of thirty years 'is' David in his being king; forty years he hath reigned;
Matthew Henry's Commentary on 2 Samuel 5:3-4
Commentary on 2 Samuel 5:1-5
(Read 2 Samuel 5:1-5)
David was anointed king a third time. His advances were gradual, that his faith might be tried, and that he might gain experience. Thus his kingdom typified that of the Messiah, which was to come to its height by degrees. Thus Jesus became our Brother, took upon him our nature, dwelt in it that he might become our Prince and Saviour: thus the humbled sinner takes encouragement from the endearing relation, applies for his salvation, submits to his authority, and craves his protection.