matter of ikhtilaf or disagreement since some Shiite scholars such as Muhammad ibn Ya'qub al-Kulayni, Ibn Babawayh, and Zayn al-Din al-Juba'i al'Amili have affirmed the date of the 12th of Rabi' al-Awal. Nonetheless, others contend that the date of Muhammad's birth is unknown and is not definitively recorded in the Islamic traditions. The issue of the correct date of the Mawlid is recorded by Ibn Khallikan as constituting the first proven disagreement concerning the celebration. History In early days of Islam, observation of Muhammad's birth as a holy day was usually arranged privately and later was an increased number of visitors to the Mawlid house that was open for the whole day specifically for this celebration. The early celebrations, included elements of Sufic influence, with animal sacrifices and torchlight processions along with public sermons and a feast. The celebrations occurred during the day, in contrast to modern day observances, with the ruler playing a key role in the ceremonies. Emphasis was given to the Ahl al-Bayt with presentation of sermons and recitations of the Qur'an. The exact origins of the Mawlid is difficult to trace. According to Muhammad in History, Thought, and Culture: An Encyclopedia of the Prophet of God, the significance of the event was established when Muhammad fasted on Monday, citing the reason for this was his birth on that day, and when Umar took into consideration Muhammad's birth as a possible starting time for the Islamic calendar. According to Festivals in World Religions, the Mawlid was first introduced by the Abbasids in Baghdad. It has been suggested that the Mawlid was first formalized by Al-Khayzuran of the Abbasids. Ibn Jubayr, in 1183, writes that Muhammad's birthday was celebrated every Monday of Rabi' al-awwal at his birthplace, which had been converted into a place of devotion under the Abbasids. According to the hypothesis of Nico Kaptein of Leiden University, the Mawlid was initiated by the Fatimids. It has been stated, "The idea that the celebration of the mawlid originated with the Fatimid dynasty has today been almost universally accepted among both religious polemicists and secular scholars." Annemarie Schimmel also says that the tendency to celebrate the memory of the Prophet's birthday on a larger and more festive scale emerged first in Egypt during the Fatimids. The Egyptian historian Maqrizi (d. 1442) describes one such celebration held in 1122 as an occasion in which mainly scholars and religious establishment