Abandoning human akhlaq (morality) originating from nature, humbling human attributes, avoiding the outbursts of the nafs (the lower self), adorning oneself with spiritual qualities, engaging with the sciences of ḥaqīqa (inner reality), and following the Messenger of God (peace be upon him) in matters of extraordinary states (sharṭat).
Shibli also says: Sufism (taṣawwuf) is to protect oneself from the material. He also said: Sufism is to be as one was before becoming a Sufi. It is also narrated that he said: The Sufi is the one who severs ties with people and unites (ittihād) with the Real (God). As Allah, in tasavvuf-ı hulki (ethical Sufism), has said:
He said: I have chosen you for Myself. (At the same time) Sufism (taṣawwuf) is to cut off ties with everything other than the Real (God). Allah has indicated this by saying: You will never see Me! (al-A'raf 7:143).
When he was asked: Why is the Sufi called ibn al-waqt (the child of the moment)? He replied: Because he does not grieve over what is lost, nor does he expect anything from what he possesses. (Rihle, 27)
Sufism (taṣawwuf) is not in reading books written on this subject, but rather in the purification and rectification of the qalb (the heart) from evil diseases, disciplining the nafs, monitoring its faults, and returning it to its original essence. (Rihle, 38)
The Sufis (ṣūfiyya) have agreed that the science of Sufism (ʿilm al-taṣawwuf) is among the subjects of jurisprudence (fiqh) and, in general, is the most noble of sciences. For its subject is to know how Allah manifests Himself through His names, attributes, actions, and judgments. This is a divine ḥikma (wisdom) that brings happiness in both dunyā (this world) and the hereafter. (Nafahāt, 21)