Assam was apprentice to the renegade sorceror Matanboukous, author of the fabled Book of Nout. Unbeknownst to his master Assam was able to copy some of the grimoire, preserving parts of the Book for posterity.
This may include Jafa'yl's Parchment:
Into the most powerful Book of all the Universes
For a moment I plunged my gaze
From the Book of Nout I stole this secret
If so this raises the question as to whom "Jafa'yl" may be, although it is possible that the name 'Assam' was replaced by 'Jafa'yl' at some point in production as the former comes from the early account of the Book of Nout from the Quantic Dream website.