Nasrabazi: To adhere to the Qur'an and hadith, not to follow one's caprice and desires, to show respect to shaykhs, to accept people's excuses, to persist in dhikr (remembrance of God), and not to resort to various interpretations regarding acts of worship.
Shibli: It is mutual love and friendship. It is to be with Allah without any anxiety. It is to listen to the inspirations of the ruh (the spirit).
Abu Saʿid: It is to abandon futile matters.
Ibn Hafif: It is sabr (patient endurance) in the face of destiny, riḍā (contentment with God's decree) with what the Truth gives, and to travel over hills and valleys in search of realities. It is to be attached to the sciences of ḥaqīqa (inner reality).
Abu Hafs: It consists of adab (proper conduct).
When we look at these definitions, selected from among hundreds, the religious aspect of the subject becomes apparent, and its ethical dimension becomes distinct.
The essence and core of the way of living and thinking that later came to be called Sufism (taṣawwuf) already existed in the era of the Prophet (peace be upon him). However, its development in the hands of the Sufis, with its own methods and procedures, institutions and organizations, as an independent science and way of life, took place in later centuries. This is also true for other Islamic sciences.
Although the fundamental cause for the emergence of the Sufi (taṣawwuf) way of life lies in the structure of religions and the spiritual needs of the human being, two movements accelerated this development. One was the emergence of luxury, debauchery, and extravagance in the Islamic world; the other was the attitude of scholars who explained religious matters solely through rationalism, neglecting its spiritual dimension. The Sufis, with their ascetic behavior, opposed the first group, and with their mystical interpretations, opposed the second group. In other words, Sufism (taṣawwuf) advanced as a reaction to these attitudes and positions.
The entry of people into Sufism (taṣawwuf) and tariqas (Sufi paths/orders) has often been explained by crisis, distress, despair, and confusion. While it is possible to find evidence for this at the individual level, it is not correct to attribute the entire movement to such causes. The real reason is found in Mawlana's analogy of the "man seeking water":
The thirsty always seek water in this world
And water, too, passionately seeks and asks for the thirsty.
Fritz Meier's interpretation is as follows: "Sufism (taṣawwuf) can be seen as an effort within the Islamic community to revive the faith fervor of the Prophet's era, to provide a return to the original authority of religion in the face of doubts, hesitations, loneliness, and confusions coming from all sides."