The article deals with investigation of a number of stories about Hasan al-Basri, a great preacher and a major representative of the zuhd movement (‘detachment’) in early Islam. These stories are gathered in anthology ‘Memorial of God’s Friends’ (Tadhkirat al-Awliya’) of the major Persian poet and Sufi thinker of XII–XIII centuries Farid ad-Din ‘Attar Nishaburi. The author provides a brief overview of the ethical ideas of Hasan al-Basri and explores the origins of his ethical doctrine. Hasan al-Basri followed the principle of strict responsibility. He was the forerunner of the Mu‘tazilite doctrine of the autonomy of human will. The focus of the article are the main themes of Hasan al-Basri’s ethical doctrine, such as: longing for higher virtues (sincerity, righteousness, piety, humility), the requirement to follow religious instructions, the overcoming attachments to the mortal world, the critique of wealth and the sermon of asceticism, etc. A detailed analysis of the stories about Hasan al-Basri and his statements allows to conclude, that there numerous ideas in his worldview later will take the form of developed Sufi ethical doctrine. The article shows, that all events from the life of Hasan al-Basri, from his birth to death, should be read and understood in the framework of his spiritual progress along a Sufi path.