Sehliyyūn (the Sehlis) are those affiliated with Sehl ʿAbd Allāh Tustarī. Sehl was among the great and eminent figures of the Sufis. In short, he was the sultan of his time. He was one of the esteemed personalities of the Sufi path (tasawwuf). He possessed many outward karāma (saintly wonders). The intellect is incapable of fully comprehending his stories. Sehl's path was one of ijtihād (independent legal reasoning), struggle with the nafs (the lower self), and ascetic discipline (riyāḍa). His murīds (aspirants, disciples) would attain the degrees of beauty (jamāl) through struggle (mujāhada).
Their method of disciplining murīds through struggle (mujāhada) and ascetic discipline (riyāḍa) is called the Sehliyyah; their service...