Abu bakr al-Kitaaniy said in defining tasawwuf, that it is manners and whomever increase on another in manners thus has more clarity and abul-Hasan an-Nawawi said, tasawwuf is not a set of rules or knowledge but manners, because if it was rules, then it would have been acquired through hard training, and if it was knowledge then it could have been achieved through studying. but it is through copying the manners of Allah. And the Shebly has defined it as its beginning is knowing Allah and its end is declaring his oneness.
And the general definition is what Abu bakr al-katani said: " Tasawwuf is clarity and observation. And Tasawwuf had started immediately with Islam and that is because it is of refined manners and a direction towards Allah in the easy parts of the deeds and the tough ones.
And from the first of the Sufis after the Sahabas and the followers are Ibrahim bin Adham and al-Fadil bin `Iyad. And because of the confusion between the people in distinguishing between an ascetic and a worshipper and a Sufi, we say:
The ascetic: The one who shuns away from the temptations of this world and its pleasures.
The worshipper: The one who is steadfast in the acts of worshipping like awaking in the night and prayer and so forth
The Sufi: The one who is the ascetic and the worshiper, because the Sufi dispense with little from this world because he abstain from having anything distract him from Allah. And the Sufi is a worshipper because of his firm and continuous connection with Allah the exalted. He worships Allah because he is worthy of worshipping and not for desire or fear.
Rabe`a al-`Adawiyya (may Allah be pleased with her): Oh my Lord, if I worship you for fear of your hell fire then throw me in it, and if I worship you in greed for your heaven then forbid me from having it and if I am worshipping you for your generous face [an Arabic expression that means for no direct or indirect benefit] then forbid me not from seeing you.
FATAWA al-Imam Abdul Haleem Mahmoud Page 334, Vol 38 - Dar al-Ifta' al-Masriyya