Shiri's Scissor

Belshazzar's Feast - John Martin, c. 1821
The mystery phrase is written in glowing letters along the top of wall at the left-center of the image.

Roberta X has a fine post that links to the story of Shiri's Scissor by Scott Alexander wherein I encounter this phrase:

Mene mene tekel upharsin

which means nothing to me so I have to go look it up, which takes me to Belshazzar's Feast on Wikipedia which is where I found the painting and an explanation of the origin of the phrase and its meaning, which is:

God has numbered Belshazzar's days, he has been weighed and found wanting, and his kingdom will be given to the Medes and the Persians.

How you get all that out of those four words is something I will leave to the experts.