2 Kings 20:15
And he said, What have they seen in thine house? And Hezekiah answered, All the things that are in mine house have they seen: there is nothing among my treasures that I have not shewed them. And he said, What have they seen in thine house? And Hezekiah answered, All the things that are in mine house have they seen: there is nothing among my treasures that I have not shewed them.
Hezekiah answered that the Babylonian visitors and ambassadors had seen everything in his house, with nothing among his treasures withheld from them. What he displayed included the treasures in God's house, which were sacred and secret things consisting of riches entrusted to him. God left him in this encounter as a test that revealed what was in his heart.
He made the display because he thought the visit and the favor of the visitors would gain him influence. Instead the display gave the Babylonians knowledge of advantages they could take for themselves, and they left planning how to take those advantages for themselves. In showing the Babylonian ambassadors the treasures in his house he began to give himself away, tempting Babylon to come and plunder them. The act was a mistake and a heinous sin of exposing himself to an enemy and betraying a sacred trust by confiding in unbelievers rather than trusting God. God pronounced a heavy judgment upon them for this disclosure.
What people possess is accountable to God, and the means entrusted to His servants are to be used to advance His work rather than withheld or diverted to personal gain or worldly enterprises. Misuse of those means leaves others without needed help and warning and brings guilt before God. The verse warns against showcasing the Lord's resources and plans to strangers and unbelievers in hope of gaining favor, and illustrates the danger of displaying valuable possessions and resources to outsiders.
Opening the Sanitarium's books to outside inspectors and to public inspection repeats Hezekiah's unwise disclosure. That disclosure was a mistake whose harm outweighed the money it brought in. Showing strangers the Sanitarium's riches likewise tested Dr. Kellogg and exposed pride and self-exaltation. Applied to homes, the question condemns keeping and displaying so many human likenesses as unnecessary and idolatrous, teaching that the money spent on photographs should instead be used to advance God's work.