Iman Gazzali (R) was the greatest sufi philosopher. He gave most importance to religious and moral teachings. He expressed through his writing that for the mental and spiritual development of human being moral teaching is essential. He established Sufism in Islam. He gave philosophical interpretations of the Islamic lawa. He wrote many fundamental books on various subjects. Among them, the most remarkable one is “Ihyau Ulum Ad-Deen”. He has established the supremacy of Islam by perfect authentic and logical descriptions, and for this reason he is regarded as “Hujjatul Islam”.