This is achieved by analyzing the text of the report, the scale of the report's transmission, the routes through which the report was transmitted, and the individual narrators involved in its transmission.
On the basis of these criteria, various Hadith classifications developed.
His death, however, gave rise to confusion over Muhammad's conduct. Due to problems of authenticity, the science of Hadith (Arabic: `Ulum al-hadith) is established.
It is a method of textual criticism developed by early Muslim scholars in determining the veracity of reports attributed to Muhammad.
To establish the authenticity of a particular Hadith or report, it had to be checked by following the chain of transmission (isnad).
The Qur'an is the holy scripture of Islam, believed by Muslims to be the direct and unaltered word of Allah.
In Islamic jurisprudence, the Qur'an contains many rules for the behavior expected of Muslims but there are no specific Qur'anic rules on many religious and practical matters.
Muslims believe that they can look at the way of life, or sunnah, of Muhammad and his companions to discover what to imitate and what to avoid. Initially, Muhammad had instructed his followers not to write down his acts, so they may not confuse it with the Qur'an.
Among Shia, Usuli school of Ja'fari jurisprudence uses four sources, which are Qur'an, Sunnah, consensus and aql.
They use ijma under special conditions and rely on aql (intellect) to find general principles based on the Qur'an and Sunnah, and use usul al-fiqh as methodology to interpret the Qur'an and Sunnah in different circumstances, and Akhbari Jafaris rely more on Hadith and reject ijtihad.