 In his preface to the "Rubáiyát", he describes Omar's philosophy as Epicurean and claims that Omar was "hated and dreaded by the Sufis, whose practice he ridiculed and whose faith amounts to little more than his own, when stripped of the Mysticism and formal recognition of Islamism under which Omar would not hide".Richard Nelson Frye also emphasizes that Khayyam was despised by a number of prominent contemporary Sufis.These include figures such as Shams Tabrizi, Najm al-Din Daya, Al-Ghazali, and Attar, who "viewed Khayyam not as a fellow-mystic, but a free-thinking scientist".