When narrators share the same name and the same father's name (and possibly further up the line), but are different persons, this is al-muttafiq wa-l-muftariq.1
Muttafiq refers to agreement in name; muftariq, to the fact that the persons themselves are different. [tr.] An example of agreement in fathers' names is six different scholars all named Khalīl ibn Aḥmad; for agreement extending further up the line, two contemporary men named Muḥammad ibn Yaʿqūb ibn Yūsuf, both of whom ʿAllāmah al-Ḥākim narrates from: one of them Abū al-ʿAbbās al-Aṣamm, the other Abū ʿAbd Allāh al-Akhram. ↩
When narrators' names are identical in writing but differ in pronunciation, this is al-muʾtalif wa-l-mukhtalif.
When the narrators' names are the same but their fathers' names differ, or vice versa, this is al-mutashābih; from it and the preceding categories various sub-types are formed.
If a narrator transmits from one of two persons who share the same name, without giving anything to distinguish him from the other, this is al-muhmal.
A ḥadīth in which a narrator has been replaced with another, whether one narrator, several, or even the entire chain, is al-maqlūb (literally, that which has been inverted).
