Ibn Taymiyah applies this principle of judicious criticism to sufi ideas, practices and personalities.
He divides the sufis into three categories:
In the first category of sufis whom he calls mashaikh al-Islam, mashaikh al-Kitab wa al-Sunnah and a'immat al-huda, [Majmu'at al-Rasa'il wa al-Masa'il, vol. 1, p. 179, and Majmu Fatawa Shaykh al-Islam, vol. 10, pp. 516-7 and vol. 11, p. 233] he mentions Fudayl b. Iyad, Ibrahim b. Adham, Shaqiq al-Balkhi, Abu Sulayman al-Darani, Maruf al-Karkhi, Bishr ëa-Hafi, Sari al-Saqati, al-Junayd b. Muhammad, Sahl b. Abd Allah al-Tustari and Amr b. Uthman al-Makki.
Later sufis whom he places in this category are: Abd al-Qadir al-Jilani, Shaykh Hammad al-Dabbas, and Shaykh Abu al-Bayan. These sufis, Ibn Taymiyah says, were never intoxicated, did not lose their sense of discrimination, or said or did anything against the Quran and the Sunnah. Their lives and experiences conformed with the Shariah (mustaqim al-ahwal) [Majmu Fatawa Shaykh al-Islam, vol. 10, pp. 516-7].
The second category consists of those sufis whose experience of fana and intoxication (sukr) weakened their sense of discrimination, and made them utter words that they later realized to be erroneous when they became sober [Majmu Fatawa Shaykh ël-Islam, vol. 10, pp. 220-1]. Some of them also did things [Majmu Fatawa Shaykh ël-Islam, vol. 10, pp. 382, 557] under intoxication of which the Shariah does not approve, but sooner or later they became sober and lived well. In this category Ibn Taymiyah mentions the names of Abu Yazid al-Bostami, Abu al-Husayn al-Nuri and Abu Bakr al-Shibli. But he condemns what they said or did in that state and offers apology for them on the ground that they were intoxicated (sukran), and had lost control over reason. [Majmu'at ël-Rasa'il wa ël-Masa'il, vol. 1, p. 168; Majmu Fatawa Shaykh ël-Islam, vol. 10, pp. 382, 557].
His criticism is directed to the third category of sufis who have believed in ideas and expounded doctrines which contradict Islamic principles [ wihdatul woojood and Al-hulool {incarnation}, or who have indulged in practices which are condemned by the Shariah.
The first sufi in this group is al-Hallaj [ the aquidah of God incarnate similar to all mushriks] [Majmu'at ël-Rasa'il wa ël-Masa'il, vol. 1, pp. 81, 83; Majmu Fatawa Shaykh ël-Islam, vol. 11, p. 18]. . . . Next to al-Hallaj the apostate, the sufis who draw strong criticism from Ibn Taymiyah are the ones who expound the doctrine of One Being or unity with God (wahdat al-wujud), such as Ibn ël-Arabi, Sadr ël-Din ël-Qunawi, Ibn Sab'in and Tilimsani. . . . . The apostate Ibn ël-Arabi, who is the central figure in this context (of wahdat ël-wujud ), Ibn Taymiyah subjects him to detailed criticism.
Ibn Taymiyah does not object to intensification of some approved forms of dhikr, or reliance on some methods for purifying the soul, with the neglect of others, provided it is within the limits of the Shariah [Majmu'at ël-Rasa'il wa ël-Masa'il, vol. 4, pp. 86-87].
It is worthwhile to note that Al-Hallaj was executed in Baghdad in 922 for saying "Ana al-Haqq" ("I am the Truth," i.e., God), and his former teacher, al-Junayd, was among those who gave the verdict that he should die. [See Abu Abd al-Rahman al-Sulami, in Tabakat al-Sufiyya, Edited by Nur al-Din Shariba, Maktaba al-Khanji, Cairo, 1986, pp. 307-8, for details.]
The third category of Sufis which includes two sub-categories, regardless of their tareeqah, worship others than Allaah, such as Prophets and “awliya’” [“saints”], living or dead. They say, “Yaa Jeelaani”, “Yaa Rifaa’i” [calling on their awliya’], or “O Messenger of Allaah, help and save” or “O Messenger of Allaah, our dependence is on you”, etc.
Also, they believe in wahdat al-wujood (unity of existence). They do not have the idea of a Creator and His creation, instead they say that everything is creation and everything is God [ Hinduism, pantheism, etc].
They unscrupulously claim that they take knowledge directly from Allaah, without the mediation of the Prophet (peace and blessings of Allaah be upon him). They say, “Haddathani qalbi ‘an Rabbi (My heart told me from my Lord).”
so the term mutassawuf or commonly known to the english world as "sufi" has quite a broad meaning. And due to ahlu-sunnah who are real or actual salafees, understanding and knowing this reality, then when ahlu-sunnah partakes in refutation of sufis, it is directed at times to the second category of sufis and most of these rududd fall in the thrid category, and not the first, However to expound on this issue and little more, the problem in our times, and for quite a while, is that most of the world that ascribe to tassawuf usually find no fault or partake in the practices either in part or in full with the tenents that are inherent in the third category of tassawuf that Haafidh Ibn Taymiyyah described.