If you don't want to know the circumstances surrounding Thursday's entry in this slideshow, then don't read any further...
[spoiler]Thursday's quote:
Ep #647 (1968) - Madame Findley - 'No. No, Mrs. Stoddard. You MUST tell nothing about this house, neither its history nor your personal experiences.'
From "Robservations 9/16/02 - #647/648 - Madame Findlay Tries to Help"
A dark-haired, exotic woman stands in Collinwood's foyer and tells Liz not to tell her anything about the house, not the history nor personal experiences. She doesn't want to know what to expect. This is Madame Findlay, a medium, and she only has her own sensitivities.
[/spoiler]
The Robservations certainly reference the quote well, though not as a direct quote or by including "must"...