Hadith expert and Shafi`ite jurist whose works, based on earlier Shafi`i authorities, have themselves become major sources of authority for Shafi`ites. (By al-Nawawi's time it was regarded as preferable for jurists to base their opinions on the works of great jurists of the past, rather than to derive them from scratch from the roots (usul) of law.) He was an ascetic devoted to scholarship, and remained unmarried (extremely unusual for even ascetic Mulsims.)