Seyyed Hossein Nasr 
Islamic Spirituality [PDF ebook] 
Foundations

Originally published 1987.The first part of the volume is concerned with "The Roots of the Islamic Tradition and Spirituality". These are seen to include the Qu’ran as the central theophany of Islam, the Prophet who received the word of God and made it known to mankind and the rites of Islam. The second part examines the divisions of the Islamic community with their distinctive pieties and emphases: Sunnism and Shi’ism and female spirituality. Part III is devoted to Sufism — its nature and origin, its early development, its various spiritual practices and its science of the soul.