The renowned scholar, Usooli and prominent Imam Abul Ma'ali Abdul Malik ibn Abdullah ibn Yusuf Ibn Muhammad al-Juwayni an-Naisaburi, was born in 419 AH /999 CE of Arab lineages going back to the tribe of Tai.
He was taught by such eminent masters in Naisabur and Marw as his own father, Abu Muhammad al-Juwayni, Abul-Qasim Al-Isfara'yni, among many others. Al-Juwayni was known for his intelligence, eloquence, learning and charisma. He began teaching in Naisabur immediately after his father's death. At the age of twenty, he taught for four years in the two Sacred-Masajid of Makkah and Madinah, and was consequently called the Imam al-Haramayn or Imam of the Two-Sacred Masajid.
Abul Ma'ali returned to his hometown, Juwayn, in Naisabur and taught for about thirty years in the Nithamiyyah School, the biggest at Naisabur in Northern Persia. He had a powerful influence on people, and he always delivered heart rendering, enlightening sermons in which he and those in attendance used to weep. He enriched the Islamic culture and research with the numerous valuable volumes, which he authored and compiled. Due to the nobility of his character and comprehensive knowledge, his students exceeded 400, including such brilliant names as al-Ghazali, al-Farawi, as-Suhami and al-Masjidi.
He was a leading scholar in Ilm al-kalam or philosophy-a framework for establishing Aqueedah that was developed after the first three generations of Muslims. But his real expertise was in Usulul (principles) of Fiqh. He wrote many books some of which still have no comparable today like, Ghayyath al-Umam (a Political treatise), al-Burhan (Fiqh Principles) and Nihayatul Matlab fi Dirayatul Math-hab (Shafi'ee School).
In the last stage of his life he came to realize that the true essence of Islam is in the words, deeds, viewpoints and ways of the righteous salaf, (the companions of the Prophet, sallallahu alayhe wa sallam, and their followers), he adopted their method again openly and boldly, and became their ardent follower. Moreover, he wrote an-Nithamiyyah Dissertation to defend and reveal the righteous belief. At the age of 59, after a life that abounded in research, education, advice and guidance, he was attacked by a severe illness that ultimately lead to his demise in 478 AH leaving many golden pages in Islamic history, full of religious knowledge, truthfulness and piety.
Shortly before dying, Imam al-Haramayn gave up on some of his teaching with regard to Aqueedah in favor of the authentic and correct methodology of the companions of the Prophet, sallallahu alayhe wa sallam. Muhammad ibn Tahir al-Maqdisi from Abu al-Alaa ibnul Fadhl that he heard Abu al-Hasan al-Qayrawani in Naisabur say: "I heard Abu al-Ma'ali say: "Dear friends! Do not occupy yourselves with kalam, if I had known where it would take me I would not have occupied myself with it. You are witnesses here that I denounce and abolish any topics or trends that may oppose or contradict the traditions of Prophet Muhammad, sallallahu alayhe wa sallam." He also said, "You are witnesses now that I refuse and refute any dissertation that doesn't comply with the explicit and implicit ways and attitudes of the righteous predecessors - the salaf. I'll die with that same direct, innate faith of Naisabur's simple old women."