This is another article in the chapter Sufism from the classical manual on Sharia called Reliance of the Traveller. The articles are posted one by one in the order they are given in the book.
w9.5 (‘Abd al-Wahhab Sha’rani:) The path of the Sufis is built of the Koran and sunna, and is based upon living according to the morals of the prophets and purified ones. It may not be blamed unless it violates an explicit statement from the Koran, sunna, or scholarly consensus (def: b7), exclusively. If it does not contravene one of these, the very most that one may say of it is that it is an understanding a Muslim man has been given, so let whoever wishes act upon it, and whoever does not refrain, this being as true of works as of understanding. So no pretext remains for condemning it except one’s own low opinion of others (dis: r2.14), or interpreting what they do as ostentation, which is unlawful. Whoever carefully examines the branches of knowledge of the Folk of Allah Most High will find that none of them are beyond the pale of the Sacred Law. How should they lie beyond the pale of the Sacred Law when it is the law that connects the Sufis to Allah at every moment? Rather, the reason for the doubts of someone unfamiliar with the way of the Sufis that it is of the very essence of the Sacred Law is the fact that such a person has not thoroughly mastered the knowledge of the law. This is why Junayd (Allah Most High have mercy on him) said, “This knowledge of ours is built of the Koran and sunna,” in reply to those of his time or any other who imagine that it is beyond the pale of the Koran and sunna.
The Folk unanimously concur that none is fit to teach in the path of Allah Mighty and Majestic save someone with comprehensive mastery of the Sacred Law, who knows its explicit and implicit rulings, which of them are of general applicability and which are particular, which supersede others and which are superseded. He must also have a thorough grounding in Arabic, be familiar with its figurative modes and similes, and so forth. So every true Sufi is a scholar is Sacred Law, though the reverse is not necessarily true.
To summarize, no one denies the states of the Sufis except someone ignorant of the way they are. Qushayri says, “No era of the Islamic period has had a true sheikh of this group, save that the Imams of the scholars of that time deferred to him, showed humility towards him, and visited him for the benefit of his spiritual grace (baraka). If the Folk had no superiority or election, the matter would have been the other way around” (alTabaqat al-kubra al-musamma bi Lawaqih alanwar fi tabaqat al-akhyar (y124), 1.4).