2 Samuel 5:10

And David went on, and grew great, and the LORD God of hosts was with him.

David had just been solemnly consecrated as king over all Israel, and his onward growth in power marked the fulfillment of God's promise to him. His greatness increased because the Lord God of hosts was with him, and that divine presence was the cause of his growing power. His rise to the throne came about through God's providence rather than through any personal ambition of his own.