TOPIbn Khaldun had all these developments before him, from the earliest Muslim ascetics, through the "ecstatic utterances" of Bistami and Hallaj, to the daring "existential monism" of Ibn al-Arabi and the theosophical speculation of his successors, when he composed his thoughts on Sufism for the Prolegomenon to History. He was well aware of the strong current of disapproval, or at least of reservation, that many in the Islamic legal establishment had expressed on the subject of Sufis and Sufism. For his part, however, Ibn Khaldun attempts to isolate the dubious areas in Sufi speculation, in the first instance by laying out the topics with which Sufis generally concerned themselves.
Many jurists and muftis have undertaken to refute these … recent Sufis. They summarily disapproved of everything they came across in the Sufi "path." The truth is that discussion with the Sufis requires making a distinction. The Sufis discuss four topics. (1) Firstly, they discuss pious exertions, the resulting mystical and ecstatic experiences, and self-scrutiny concerning one's actions. They discuss these things in order to obtain mystical experience, which then becomes a station from which one progresses to the next higher one. … (2) Secondly, they discuss the removal of the veil and the perceivable supernatural realities, such as the divine attributes, the throne, the seat, the angels, revelation, prophecy, the spirit, and the realities of everything in existence, be it supernatural or visible; furthermore, they discuss the order of created things, how they issue from the Creator Who brings them into being. … (3) The third topic is concerned with activities in the various worlds and among the various created things connected with the different kinds of divine grace. (4) The fourth topic is concerned with expressions which are suspect if understood in their plain meaning. Such expressions have been uttered by most Sufi leaders. In Sufi technical terminology they are called "ecstatic utterances." Their plain meaning is difficult to understand. They may be something that is disapproved of, or something that can be approved, or something that requires interpretation.
Now that the territory has been charted, Ibn Khaldun can proceed to his critique. First, on the matter that by all accounts constituted the mainstream of Sufism and which had won, at least since the time of Ghazali, a recognized place among acceptable Islamic practices and experiences:
As for their discussion of pious exertions and stations, of the mystical and ecstatic experiences that result, and of self-scrutiny with regard to shortcomings in the things that cause these experiences, this is something that nobody ought to reject. These mystical experiences are sound ones. Their realization is the very essence of happiness.
Ibn Khaldun then reverses the second and third points he had established above, treating first the Sufis' perceptions about the operation of divine grace, which he is inclined to accept, and their description, after the "removal of the veil," of that other, higher world where God and His angels and the other higher realities have their being, about which he is much less certain.
As for their discussion of the acts of divine grace experienced by the Sufis, the information they give about supernatural things, and their activity among created things, these are sound and cannot be disapproved of, even though some religious scholars tend to disapprove … since they might be confused with prophetic miracles.
There is no problem here. The scholastic apparatus of theology had its distinctions well in order.
Competent orthodox scholars have made a distinction between (miracles and acts of divine grace) by referring to "the challenge (in advance)," that is, the claim made (by the prophet in advance) that the miracle would occur in agreement with the prophetic revelation. It is not possible, they said, that a miracle could happen in agreement with the claim of a liar. Logic requires that a miracle indicate truthfulness. By definition a miracle is something that can be verified. If it were performed by a liar it could not be verified and thus would have changed its character, which is absurd. In addition, the world of existence attests the occurrence of many such acts of divine grace. Disapproval of them would be a kind of negative approach. Many such acts of divine grace were experienced by the men around Muhammad and the great early Muslims. This is a well-known and famous fact.
The Sufis' charting of the higher realities, on the other hand, might appear to constitute a kind of private, intuitive and so unverifiable revelation. In this case Ibn Khaldun recommends a kind of circumspect neglect.
Most of the Sufi discussion about the removal of the veil of the reception of the realities of the higher things, and of the order in which the created things issue, falls, in a way, under the category of ambiguous statements. It is based upon the intuitive experience of the Sufis, and those who lack such intuitive experience cannot have the mystical experience that the Sufis receive from it. No language can express what the Sufis want to say in this connection, because languages have been invented only for the expression of commonly accepted concepts, most of which apply to sensible reality. Therefore, we must not bother with the Sufi discussion of those matters. We ought merely to leave it alone, just as we leave alone the ambiguous statements in the Quran and the Prophetic custom. Those to whom God grants some understanding of these mystical utterances in a way that agrees with the plain meaning of the religious law do, indeed, enjoy happiness. (Ibn Khaldun, Muqaddima 6.16) [IBN KHALDUN 1967: 3:99–101]