Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
The fundamental Islamic sources such as the Qur’an and the core traditions of the Prophet (peace and blessings be upon him) have been fully preserved intact. This can be demonstrated easily by referring to the sound historical methodologies in verifying the sources.
There is a basic distinction between Islam and other religions in this regard: Islam is singularly unique among the world religions in the fact that in order to preserve the sources of their religion, the Muslims invented a scientific methodology based on precise rules for gathering data and verifying them.
As it has been said, “Isnad or documentation is part of Islamic religion, and if it had not been for isnad, everybody would have said whatever he wanted.”
So, there is no comparison between the sources of Islam and those of other religions in this respect, as you will never find anything comparable to the many sciences Muslims invented for this noble task of preserving the sources of Islam. By virtue of such sciences, you can scrutinize and verify every report in the sources.
Thanks to these efforts, the Qur’an as well as the core tradition on which the Islamic faith and practices are based, have been fully protected.
In this context, it should be added that the process of recording Hadith started as early as the time of the Prophet (peace and blessings be upon him). Actually, many Companions recorded hadiths, and, `Abdullah ibn `Amr, for example, was permitted and even encouraged by the Prophet (peace and blessings be upon him) to write down Hadith. In addition, some 50 Companions and many Successors are said to have possessed manuscripts (sahifah, Arabic plural suhuf), which was used as a term to designate compendia of Hadith that emerged during the century before the formation of the classical collections.