In the Classical tradition of Islam, the science of this inner purification is referred to as Tasawwuf. It is the Islamic sacred science that concerns itself with curing the hearts of spiritual afflictions and attaining the love and nearness of Allah the Exalted.

Sufism existed as an individual inner practice of Muslims since early Islamic history. According to Carl W. Ernst the earliest figures of Sufism are Muhammad (pbuh) himself and his companions (Sahabah). Sufi orders are based on the bay‘ah (bay‘ah, mubaya‘ah 'pledge, allegiance') that was given to Muhammad (pbuh) by his Sahaba. By pledging allegiance to Muhammad (pbuh), the Sahabah had committed themselves to the service of God

Sufism’s claim to universality is founded on the broad recognition that there is only one God, the God of all people and all true religions. Sufism understands itself to be the wisdom realized by the great prophets — explicitly including Jesus, Moses, David, Solomon, and Abraham, among others, and implicitly including other unnamed enlightened beings of every culture.

If Sufism recognizes one central truth, it is the unity of being, that we are not separate from the Divine. The unity of being is a truth which our age is in an excellent position to appreciate — emotionally, because of the shrinking of our world through communications and transportation, and intellectually, because of developments in modern physics. We are One: one people, one ecology, one universe, one being. If there is a single truth, worthy of the name, it is that we are all integral to the Truth, not separate. The realization of this truth has its effects on our sense of who we are, on our relationships to others and to all aspects of life. Sufism is about realizing the current of love that runs through human life, the unity behind forms.

If Sufism has a central method, it is the development of presence and love. Only presence can awaken us from our enslavement to the world and our own psychological processes. And only love, cosmic love, can comprehend the Divine. Love is the highest activation of intelligence, for without love nothing great would be accomplished, whether spiritually, artistically, socially, or scientifically.