the designation “Sufi” is related—for it is a relational adjective, like Qurashī (of Quraysh), Madanī (of Medina), and the like.
It has been said that it derives from “Ahl al-Suffa” (the people of the sheltered platform). This is incorrect, for in that case the form would have been Suffī. It has also been said that it derives from the foremost rank before Allah. This too is incorrect, for in that case the form would have been Saffī. Another suggestion is that it derives from the chosen among Allah’s creation. This is incorrect, for in that case the form would have been Safawī.
It has also been said that it derives from Sūfa ibn Murr ibn Udd ibn Tānja, an Arab tribe whose members had resided in Mecca since ancient times, and to whom devout worshippers were said to be affiliated. Although this derivation is sound in form, it too is weak. These people are neither widely known nor familiar to most devout worshippers. Moreover, had devout worshippers been affiliated with them, this designation would more fittingly have existed in the time of the Companions, their successors, and the generation after them. Furthermore, most of those who have used the designation “Sufi” do not know this tribe and would not accept affiliation with a tribe from the pre-Islamic age of ignorance that has no existence in Islam.
It has also been said—and this is the well-known explanation—that it derives from wearing wool. The Sufis first emerged in Basra, and the first small Sufi lodge was built by some of the companions of ʿAbd al-Wāhid ibn Zayd. ʿAbd al-Wāhid was one of the companions of al-Hasan. In Basra there was an intensity of asceticism, worship, fear of Allah, and the like