Hizir Bey was born around 810/1407 in Sivrihisar near Eskişehir, the son of the kadı Celâleddin Efendi. He taught in Sivrihisar, Bursa and at the Üç Şerefeli Mosque Medrese in Edirne, and was called "the second Ibn Sina" for his mastery of theology and logic. Immediately after the conquest of Istanbul in 1453, Sultan Mehmed the Conqueror appointed him the new capital's first kadı (chief judge). Because he regulated municipal, security and urban-development affairs as well as the judiciary, he is also remembered as Istanbul's first "mayor." He left works on kalam, most famously the "Kaside-i Nuniyye," and raised scholarly sons such as Sinan Paşa and Ahmed Paşa. He died in Rebiulevvel 863 (January 1459) and was buried in the cemetery in the Vefa-Zeyrek quarter.