MrKnickerbocker
clap hands
It's number is six-hundred and sixty-six.
The Number of the Beast.
The Number of the Beast.
Though I bet just the fact that it's a king isn't the answer here...
Let me make another guess, just going by the title of the painting (Judgement of Solomon) and guess that the clue is as simple as a shared word in the title?
Judgement of Heaven?
Is the clue related to the biblical story, though? Or is it related more directly to something we see in the painting?