—foremost among them al-Ḥāfiẓ Ibn Ḥajar (may Allah have mercy on him).

If someone were to ask, “How do we distinguish one case from the other?” we reply:

With the muʾtalif–mukhtalif the distinction is easy, for the names diverge in pronunciation. Confusion only arises if we follow the practice of the early scholars, who wrote without iʿjām—that is, without the dots that differentiate the letters.

For instance, to the earliest scholars the words ʿAbbās and ʿAyyāsh looked identical, for the script carried neither vowel marks nor dots. Among later scholars the possibility of confusion is far smaller because they supply the diacritics.

The muttafiq–muftarq, however, remains difficult even in modern times, for identifying the narrator intended requires painstaking investigation into the individual himself and a precise profile of him.

The benefit of mastering this discipline, then, is to pinpoint the narrator so that we may determine whether to accept or reject his report. One turns for that to the specialized works written on the subject, and among the greatest aids to identifying a transmitter are knowing his teachers—those from whom he narrates—and his students—those who narrate from him.