„The ancient Sufis did not go into anything concerned with (the Mahdi). All they discussed was their (mystic) activity and exertion and the resulting ecstatic experiences and states. It was the Imamiyah and the extremist Shi’ah who discussed the preferred status of ‚Ali, the matter of his imamate, the claim (made in his behalf) to have received the imamate through the last will (of the Prophet), 949 and the rejection of the two Shaykhs (Abu Bakr and ‚Umar), as we have mentioned in connection with the discussion of Shi’ah dogmatics.950 Thereafter, there originated among them the dogma of the Infallible Imam 951 Much was written on (Shi’ah) dogmatics. The Isma’iliyah Shi’ah made its appearance. It asserted the divinity of the imam through incarnation. Others asserted that the (dead) imams would return, either through metempsychosis or (in the very form they had had during their lifetime). Still others expected the coming of imams who would be cut off from them through death. Others, finally, expected that the family of Muhammad would return to power. They deduced this from the afore-mentioned traditions concerning the Mahdi, and from other traditions.
Among the later Sufis, removal (of the veil, kashf) and matters beyond the veil of sense perception likewise came to be discussed. A great many Sufis came to speak about incarnation and oneness. 951a This gave them something in common with the Imamiyah and the extremist Shi’ah who believed in the divinity of the imams and in the incarnation of the deity in them. The Sufis also came to believe in a „pole“ (qutb) and in „saints“ (abdal). This (belief) looked like an imitation of the opinions of the extremist Shi’ah concerning the imam and the ‚Alid „chiefs“ (nugabd‘).952
The Sufis thus became saturated with Shi’ah theories. (Shi’ah) theories entered so deeply into their religious ideas that they based their practice of using a cloak (khirgah) on the (alleged) fact that ‚Ali clothed al-Hasan al-Basri in such a cloak and caused him to agree solemnly that he would adhere to the mystic path. (The tradition thus inaugurated by ‚Ali) was continued, according to the Sufis, through al-Junayd,953 one of the Sufi shaykhs.
However, it is not known with certainty that ‚Ali did any such thing. The (mystic) path was not reserved to ‚Ali, but all the men around Muhammad were models of the (various) paths of religion. The fact that (the Sufis) restrict (precedence in mysticism) to ‚Ali smells strongly of pro-Shi’ah sentiment. This and other afore-mentioned Sufi ideas show that the Sufis have adopted, pro-Shl’ah sentiments and have become enmeshed in them.“