Sufism
Webster's Dictionary [1]
(n.) A refined mysticism among certain classes of Mohammedans, particularly in Persia, who hold to a kind of pantheism and practice extreme asceticism in their lives.
The Nuttall Encyclopedia [2]
The doctrine of the Sufis, a sect of Mohammedan mystics; imported into Mohammedanism the idea that the soul is the subject of ecstasies of Divine inspiration in virtue of its direct emanation from the Deity, and this in the teeth of the fundamental article of the Mohammedan creed, which exalts God as a being passing all comprehension and ruling it by a law which is equally mysterious, which we have only to obey; this doctrine is associated with the idea that the body is the soul's prison, and death the return of it to its original home, a doctrine of the dervish fraternity, of which the Madhi is high-priest.