Muslims gather outside the Abu Hanifa mosque in the Adhamiya district north of Baghdad, Iraq, on Dec. 22, 2015, to celebrate the birthday of the Prophet Muhammad. Prophet Muhammad's birthday is observed by Sunni Muslims on the 12th of Rabi' Al-Awwal, the third month in the Islamic lunar calendar, or on the 17th of the same month by Shiite Muslims. (Xinhua/Khalil Dawood)

Muslims gather outside the Abu Hanifa mosque in the Adhamiya district north of Baghdad, Iraq, on Dec. 22, 2015, to celebrate the birthday of the Prophet Muhammad. Prophet Muhammad's birthday is observed by Sunni Muslims on the 12th of Rabi' Al-Awwal, the third month in the Islamic lunar calendar, or on the 17th of the same month by Shiite Muslims. (Xinhua/Khalil Dawood)

Muslims gather outside the Abu Hanifa mosque in the Adhamiya district north of Baghdad, Iraq, on Dec. 22, 2015, to celebrate the birthday of the Prophet Muhammad. Prophet Muhammad's birthday is observed by Sunni Muslims on the 12th of Rabi' Al-Awwal, the third month in the Islamic lunar calendar, or on the 17th of the same month by Shiite Muslims. (Xinhua/Khalil Dawood)

Iraqi Parliament Speaker Salim al-Jubouri (C) and other officials attend the celebrations in the Abu Hanifa mosque in the Adhamiya district north of Baghdad, Iraq, on Dec. 22, 2015, to celebrate the birthday of the Prophet Muhammad. Prophet Muhammad's birthday is observed by Sunni Muslims on the 12th of Rabi' Al-Awwal, the third month in the Islamic lunar calendar, or on the 17th of the same month by Shiite Muslims. (Xinhua/Khalil Dawood)