Sa'd ibn Ubadah
Muhammad ibn Muhammad was born on 15 August 1257 (Wednesday 3 Shaban 655 AH) in Granada. His father was the future Muhammad II and his mother was his father's first cousin (a bint 'amm marriage). They belonged to the Nasrid clan—also known as Banu Nasr or Banu al-Ahmar—which according to later Granadan historian and vizier Ibn al-Khatib, was descended from Sa'd ibn Ubadah. Sa'd was a prominent companion of the Islamic prophet Muhammad, from the Banu Khazraj tribe in Arabia; his descendants migrated to Spain and settled in Arjona as farmers. The future Muhammad III was born during the reign of his grandfather, Muhammad I, the founder of the dynasty. Earlier in the same year, his father was named heir of the emirate. Muhammad III had a sister, Fatima, born from the same mother. Their father had a second wife, a Christian named Shams al-Duha, who was mother to their much younger half-brother Nasr (born 1287). Their father, also known by the epithet "al-Faqih" ("the canon-lawyer") due to his erudition and education, encouraged intellectual activities in his children: Muhammad was intensively engaged in poetry, while Fatima studied the "barnamaj"—the biobibliographies of Islamic scholars—and Nasr studied astronomy.