VARIOUS OF LOCATIONS, TURKEY - JULY 20: Millions across Turkey on Tuesday (July 20) performed special prayers on the first day of the Muslim holiday Eid al-Adha.In the historic metropolis of Istanbul, Hagia Sophia Grand Mosque, which last year reopened for worship, witnessed the first Eid prayers, also known as Salat al-Eid, for the feast of the sacrifice holiday.Most majority-Muslim countries around the world, including Turkey, will observe the four-day holiday starting on Tuesday.The holiday commemorates the willingness of the Prophet Ibrahim, or Abraham, to sacrifice his son at the command of God, before the last-minute divine substitute of a ram.Muslims sacrifice animals in commemoration of this intervention and share the meat with the poor and their relatives.