The Book of Certainty (häftad, eng)

''To express in the language of Sufism, that is, Islamic mysticism, some of the universal truths which lie at the heart of all religions''—this is the book''s avowed purpose. It came into being because the author was asked by a friend to set down in writing what he considered to be the most important things that a human being can know.

He was also asked to make it very easy, and despite the depth of all that it contains, it has in fact a remarkable simplicity and clarity, due no doubt to the constant use of traditional imagery which awakens and penetrates the imagination.