Ar-Risalah

الرسالة

The first systematic treatise on Islamic legal theory (usul al-fiqh) ever written. Imam ash-Shafi'i laid out the foundations of how to derive legal rulings from the Quran, Sunnah, ijma (consensus), and qiyas (analogical reasoning). He established the hierarchy of legal sources and the principles of abrogation, general versus specific texts, and the authority of the Sunnah. Every later work of usul al-fiqh builds upon the framework established in this groundbreaking text.