"The emergence of the difference in practical legal rulings is due to the emergence of ijtihad, which began easy during the era of prophethood ...", then expanded in "the era of the Companions, for the interruption of the revelation and the distribution of the Companions (may God be pleased with them) in Al -Amsar." This difference is first due to the multiplicity of meanings that the texts bear on the one hand, and then to "the difference of perceptions, understandings and minds." The diligent imams differed in the interpretation of the provisions of the Qur''an and Sunnah, as well as those who came after them from scholars and jurists. Imam Abu Ja`far Ahmad bin Muhammad al -Tahawi collected "the sayings of the diligent jurists in a great travel", "He does not believe in his time, so he described his huge and his capacity that he is located in a hundred and thirty and thirty parts ..", "The best of his abbreviation after Imam Abu Bakr Ahmed bin Ali Al -Jasas Al -Razi, and commented on some of the sayings of Al -Tahawi and others with scientific criticism and comment, while maintaining the beauty of the origin and its spirit .. "
