and the purity of their actions, that is, the outward aspect (their behavior) being cleansed from opposition to divine commands. Undoubtedly, this is also due to their inner secrets being purified from all turbidity.
As for the view that they are called Sufi because they wear ṣūf (woolen garments), this is one opinion. However, this group did not distinguish themselves by wearing woolen garments out of humility alone. They did not wear only wool, but also wore garments made from fabrics such as cotton. Moreover, if a person wears woolen clothing in order to make people believe he is a Sufi, sālik (traveler on the path), or ascetic (zāhid), and to gain respect and attention, this is considered a blameworthy act of ostentation (riyāʾ). (Bughyat, 17)
Much has been said about the etymology of the word Sufi. Some among the Sufis have said it is derived from safā (purity). For Sufis are the chosen servants of Allah who purify their hearts from the turbidity of worldly life.
Sirī al-Saqaṭī says: The name mutaṣawwif (one who practices Sufism) has three meanings: He is one whose light of maʿrifa (gnosis, experiential knowledge of God) does not extinguish the light of his waraʿ (scrupulous piety); who does not speak contrary to the outward aspect of the Book and Sunnah in his inner knowledge; and who does not claim to possess karāma (a saintly wonder) by violating the prohibitions set by Allah. Sahl ʿAbd Allāh al-Tustarī also says: Sufi is derived from safā, meaning one whose heart is purified from sorrow (turbidity). Thus, he is filled with contemplation, has severed ties with mankind, and for him, gold and earth are the same.
Abū Ḥusayn al-Nūrī says: Sufism (taṣawwuf) is neither knowledge nor form. Rather, it is akhlāq (noble character). If it were form, it could be attained through striving (mujāhada). If it were knowledge, it could be acquired through learning. But it is to be adorned with the character of Allah. Your power is not sufficient to approach the divine character through knowledge and form. He also says: Sufis are those who have purified their hearts from human sorrows and the afflictions of the nafs (the lower self). They have become so free from their own desires that they are neither mālik (possessors) nor mamlūk (those who are possessed, slaves, or dependent on others).
Junayd says: Sufism (taṣawwuf) is the purification of hearts until they never return to weakness again.