Based on Shi'i point of view, "Hadith" refers to the sayings or "traditions" which have been transmitted from the Prophet (P.B.U.H.) and infallible Imams (A.S.). Muslims in general and Shi'is in particular hold these to be the most important source of Islamic teachings after the Qur'an.
In most of Islamic studies especially the western ones, meaning of Hadith has been limited to the point of view of Sunni Islam, which considers Hadith only as the sayings and deeds of Prophet (P.B.U.H.). Practically no one has paid any serious attention to the different nature of the Hadith literature in Shi'ism and the different sources from which the Hadiths are derived.
Some of the others that are not really familiar to shiism reflect this difference wrongly as shi'i believe on Hadiths which are traced only through 'Ali's family, Or some others say that Shi'is don’t accept Sunni Hadith collection because they do not reject Abubakr, Omar or those who entered war against Imam Ali (A.S.). But this is incorrect. Shi'i scholars insist on some conditions to accept a hadith as authentic.Whatever hadith that has this principle and logical conditions, would be authentic.
Among different Hadith collections, Shi'is believe that four Hadith collections are more authentic and reliable. Kitab al-Kafi by Muhammad ibn Ya’qub al-Kulaini, Man la yahduruhu al-Fagih by Muhammad inb Babuye, Tadhib al-Ahkam by Sheykh Muhammad Tusi, and Al-Istibsar by the same writer are this four book.
Here, we will describe the book Al-Kāfī (The Sufficient Book) in brief. Al-Kafi is a collection of the traditions taught by the Prophe (P.B.U.H.) and the Imams (A.S.) and handed down to the Muslim Community by the disciples of the Imams. The author of al-Kafi is thiqat al-Islam, Abu Ja'far Muhammad b. Ya'qub b. Ishaq al-Kulaini al-Razi. The number of Hadith in this book based on different sources has been reported from 151769 to 15 1818. 5,072 of this hadiths are considered sound (sahih), 144 are regarded as good (hasan), 178 are held to be trustworthy (muwaththaq), 302 are adjudged to be strong (qawi), and 9,484 are considered weak (da'if). This book is divided into three parts :
• Usūl al-Kāfī: this part consists of a collection of Hadiths on epistemology, theology, history, ethics, supplication, and the Qurʾān. The main topics which has been discussed in this part are Reason and Ignorance (al-aql wal jahl), Knowledge (al-ilm), Monotheism (at-Tawhid), Demonstrative Proof and Reasoning, Belief and Disbelief, Supplication (Dua), The Virtues of the Qur’an, Usul (the Fundamentals) of Kafi. all this topics has been gathered in two volumes.
• Furūʿ al-Kāfī: this part is about practical and legal issues. The main focus of the writer in this part is on branches. This part is the largest part of al-Kafi. Main topics in this part are devoted to rules of conduct about purification, menstruation, Corpses, Ritual Prayer, Alms and Charity, Fasting, the Pilgrimage (Hajj),Jihad, Earning Livelihood, Marriage, Sacrifice Offering on the Seventh Day of a Newly Born Child, Divorce, Emancipation and Management and Correspondence, Hunting and Fishing, Sacrificial Slaughter, Foods, Drinkables, Luxury and Generosity, Quilts [or Beddings], Wills and Testaments, Inheritance, Prescribed Penalties, Blood Money, Witnesses, Duties and Laws, Faith and Vows and Disbelief. This topics have been collected in 5 volumes.
• Rawdat (or Rauda) al-Kāfī: this part includes miscellaneous traditions, many of which are The Sermons or Recitations of infallible Imams. Some of the topics in this part are Hermeneutics and interpretation of some of the verses of the Gloriuos Qur’an, The advices and recommendations of the Imams (a), Dreams and their Kinds, Pains and their Cures, The Quality of the Creation of the Existing World and some of its Manifestations, The History of Some of the Prophets (a), The Virtues of the Shiites and their Duties, Some of the Issues in regard to the Early Days of Islam and the Period of the Caliphate of Amir al Mu’mineen (a), Mahdi (a) and his attributes and also his Companions and the characteristics of the Period of the Re-appearance, The history of some of the companions and individuals like Abu Thar, Thamama bin Athal, Zaid bin Ali, Salman, Ja’far bin Abi Talib. This hadith has been collected in 1 volume.
Al-Kulaini said in the introduction part about his book that :
“...You wanted to have a book which would be sufficient (for your religious needs) (kafin), which would include all kinds of knowledge ('ilm) of religion, which would be adequate for the student, and to which the teacher might refer. Thus it could be used by anyone who wanted knowledge of religion and of legal practice ('amal) according to sound traditions (athar) from the truthful ones (the Imams) ...”
AlHur Al'amily, a muhaddith and a prominent Twelver Shi’a scholar, said " The authors of the Four Books of shia ( Alkafi , AlIstibsaar , AlTahzeeb , Mun La YahDuruHu Alfaqeeh ) have testified that the Hadiths of their books are accurate (saheeh) , firm and well conducted from the roots that all shia agreed on , and if you consider those scholars ( the authors of the four books ) are reliable then you must accept their sayings and their narrations . " [ Alwasa'el , volume 20 , page 104 ]
Sharaf'Deen AbdulHussain Mosawy said : " Alkafi , AlIsTibSaar , AlTahzeeb and Mun La YahduRuHu Alfaqeeh are *MutawaTirah* and agreed on the acuraty of its contents ( the Hadiths ) , and Alkafi is the oldest , greatest , best and the most accurate one of them " . [ The book of AlMuraja'aat , Muraj'ah number 110 ] ..... MutawaTirah = accurate 100% because it was narrated by many narrators .
Al-Kafi, has been translated into English by the World Organization for Islamic Services.