In those days it was commonly easy: a Companion would hear a ḥadīth directly from the Messenger of Allah ﷺ, then a Successor would hear that ḥadīth directly from the Companion, and so on. When we pause at the first three generations whose excellence has been testified to, we may ask: was there anything known as ʿilm al-ḥadīth (hadith science)? The answer is no. Was there anything known as ʿilm al-jarḥ wa al-taʿdīl (the science of narrator criticism and accreditation)? Again, no. Today, however, a student of knowledge cannot dispense with these two disciplines; they are communal obligations, for through them the scholar can determine whether a ḥadīth is authentic or weak. Matters are no longer as straightforward as they were for a Companion, who took the narration from other Companions whose integrity Allah Himself affirmed… and so forth. What was easy then is no longer easy today with regard to the purity of knowledge and the reliability of its sources. Therefore we must take this into account and accord it the attention it deserves, in a way that meets the challenges surrounding us as Muslims—challenges that did not beset the earliest Muslims—namely the doctrinal contamination that has generated problems and produced doubts at the hands of the people of innovation who have deviated from the sound creed and the path of truth under many banners, among them the cry, “We call to the Qur’an and Sunnah only!”—as is alleged by those who attach themselves to the science of