Imam Muhammad al-Syafie, his great contribution was the codifying and organization of a concept known as usul al-fiqh(the principles behind the study of fiqh). During his illustrious career, he learned under some of the greatest scholars of his time, and expanded on their ideas, while still holding close to the Quran and Sunnah as the main sources of Islamic laws. Today, his madhab (school of thought), is the second most popular on earth, after the madhab of Imam Abu Hanifa.