The book of the letter to Imam Al -Shafi'i is the first book Ala in the Form of Fundamentals of Jurisprudence. Al -Shafi'i wanted - by composing this book to set the controls that the jurist or the diligent committed to clarifying the legal rulings for each hadith and created in every era. It is one of the books that Al -Rabee narrated from Al -Shafi'i