The principles of Hadith, their rulings, and the explanation of jurists' views, their doctrines, and terms are reported from the benefits deducted by scholars from their books and writings which I benefited such as the book of "At-Talkhis" of Imam Al Haramayn Abu Al Ma`aly Al Juwayny, the book of "Al Mustasfa" of scholar Abu Hamid Al Ghazaly, the book of "At-Taqwim" of Abu Zayd Ad-Dabbusy, the book of "Usuul Al Hadith" of Al Hakim Abu `Abdullah Muhammad ibn `Abdullah An-Naysabury and his book "Al Madkhal Ila Al Iklil," part of the letters of Al Khatib Abu Bakr ibn Thabit Al Baghdady, the book of "Al `Ilal" of Imam Abu `Eisa At-Tirmidhy, besides other books and writings.
So, I collected all these sayings, abridged them to be in harmony with this introduction, and wrote the things needed by the science of Hadith students and things which they cannot miss except if they are satisfied with narrations only without paying attention to the core of the science itself.
I only arranged, abridged, collected, and chose these sayings, however sometimes I add some words in the middle of sections and chapters that include new information, explanation, verification, detailing, or confining a general meaning, and included four chapters in this section.