John Gill Commentary 1 Kings 3:8

"And thy servant is in the midst of thy people which thou hast chosen, a great people, that cannot be numbered nor counted for multitude." — 1 Kings 3:8 (ASV)

And your servant [is] in the midst of your people which you have
chosen
To be his special and peculiar people above all people on the earth; this is not to be understood locally, though Jerusalem, where his palace was, was in the middle of the land; but of the exercise of his office, he being placed over the people, and among them, and having the care and inspection of them:

a great people, that cannot be numbered or counted ;
being for number as the stars in the sky, and as the sand upon the seashore, as had been promised.