Imam al Abu 'l Qasim al-Qushayri [d.465h/1074C.E.],
Abd al-Karim ibn Hawazin al-Qushayri, may Allah be pleased with him, is from Nishapur (Khurasan district) in what is today Iran. Al-Qushayri was a famous Sunni scholar and mystic (sufi). He was a disciple of the Sufi master Abu Ali ad-Daqqaq, may Allah be pleased with him, who had been a student of al-Sulami. Al-Qushayri, may Allah be pleased with him, was a recognised muhaddith who transmitted hadith to pupils by the thousands in Naysabur, as well as a mufassir who wrote a complete commentary of the Qur'an entitled 'Lata'if al-isharat bi tafsir al-Qur'an' (The subtleties and allusions in the commentary of the Qur'an).
His "Risala ila al-sufiyya" or "Epistle to the Sufis" is so widely read in Sufi circles that it is often called the "Treatise of Qushayri" or simply "Treatise," no other name required. It is a Sufi textbook of the highest order where Sufi practices, states and stations, rules of travel, dreams and advice to the spiritual seeker, among other topics are related to Qur'anic verses, traditions of the Beloved Prophet Muhammad, Peace and Blessings of Allah upon him, and sayings of early Sufis. The Risala is an interwoven collection of brief essays on Sufism and mystical experience, often accented with anecdotes, sayings, and poetry. Its insight, clarity, and readability make it one of the most respected and studied early works on the Sufi way.
This was a book that Mawlana Jalal al-Din Rume, may Allah be pleased with him, read and recommended to his students. 'The Risalah' has been described as one of the early complete manuals of the science of tasawwuf.