John Gill Commentary 2 Samuel 5:12

"And David perceived that Jehovah had established him king over Israel, and that he had exalted his kingdom for his people Israel`s sake." — 2 Samuel 5:12 (ASV)

And David perceived that the Lord had established him king
over Israel
By the prosperity and success which attended him in everything he set his hand to:

and that he had exalted his kingdom for his people Israel's sake ;
for their advantage and glory more than for his own.