that, relating certain reports into which errors had crept(1). Most of what he related, however, was sound, and reliable narrators such as al-Layth and his peers concurred with him concerning it.

Hadith scholars know the truth of the texts in the two Sahih collections. They also know the falsity of those fabricated hadiths which they state with certainty are lies, on the basis of evidence by which they recognized them as such. Those who share their familiarity with this evidence know what they know, whereas those who do not share it do not know this. In the same way, anyone who has tested and come to know witnesses who bear and give testimony can recognize the (truthfulness of) those among them who are truthful and the (mendacity of) those who lie(2). Similarly, among those engaged in transactions involving sales and leases, anyone who has dealt with and come to know them can distinguish those who tell the truth from those who lie, and the trustworthy from the treacherous. Likewise, people may know some reports to be true and others to be false, while remaining uncertain about still others.

As for knowledge of reports from the Prophet—may Allah bless him and grant him peace—his statements and actions, and what he mentioned concerning the oneness of Allah, commands and prohibitions, promises and threats, the merits of deeds or groups of people(3), places or times(4), and the corresponding demerits of such things, those best versed in all of this are the scholars of his hadith. They exerted themselves to acquire and investigate this knowledge through its various channels, learned the circumstances of its transmitters and the circumstances of the Messenger—may Allah bless him and grant him peace—from numerous perspectives, and brought together the narrations of one person, another, and yet another. They thereby discerned the truthfulness of the truthful, the error of one who erred, and the lie of the liar.

This is a field of knowledge for which Allah has raised up people through whom He has preserved(5) for the Ummah what He has preserved of its religion, and those other than