Uthman ibn Affan (Arabic: عثمان بن عفان‎, translit. ʿUthmān ibn ʿAffān‎), also known in English by the Turkish and Persian rendering, Osman, (579–17 June 656), was a companion of the Islamic prophet Muhammad and the third of the Rashidun, or "Rightly Guided Caliphs." Born into a prominent Meccan clan of the Quraysh tribe, he played a major role in early Islamic history, succeeding Umar ibn al-Khattab who died in office at the age of 59/60 years as caliph at the age of 64/65 years (the second-oldest ruler).

According to Sunni Muslims Uthman was married to Ruqayyah, and then upon her death, married Umm Kulthum, both of them being daughters of Prophet Muhammad, which earned Uthman the honorific title Dhū al-Nurayn ("The Possessor of Two Lights").

Under the leadership of Uthman, the empire expanded into Fars (present-day Iran) in 650, and some areas of Khorasan (present-day Afghanistan) in 651. The empire's conquest of Armenia began by the 640s.

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