Al-Nizamiyya of Baghdad (Arabic: المدرسة النظامية), one of the first nizamiyehs,[1] was established in 1065 in Baghdad. The Nizamiyya School was considered among the most important and prestigious educational institutions of the Abbasid era, along side with the Mustansiriya School. It has been described as the "largest university of the Medieval world."[2] The Nizamiyya school was completely Shafi'i. One of its requirements was that all teachers, preachers, and librarians be Shafi'i in jurisprudence and Ash'ari in theology. This school was home to prominent Shafi'i jurists including Abu Ishaq al-Shirazi, Ibn al-Sabbagh, Abu Sa'ad al-Mutawalli, Abu Hamid al-Ghazali, and Al-Kiya al-Harrasi.[3][4]
The Persian poet Saadi Shirazi studied at the nezamiyeh during the early 13th century, when he set out on a journey. He was also among those who witnessed first-hand accounts of its destruction by Mongol Ilkhanate invaders led by Hulagu during the Sack of Baghdad in 1258. He recalls clearly his days of studies at the al-Nizamiyya in Baghdad "A fellow-student at Nizamiah displayed malevolence towards me, and I informed my tutor, saying 'Whenever I give more proper answers than he the envious fellow becomes offended.' The professor replied 'The envy of thy friend is not agreeable to thee, but I know not who told thee that back-biting was commendable. If he seek perdition through the path of envy, thou wilt join him by the path of slander.'"[page needed]