would likewise have been classed as mudallis; for they undeniably lived in the Prophet’s ﷺ lifetime, yet it is not (1) known whether they ever met him.
Among those who required (2) an actual meeting for tadlīs are: Imām al-Shāfiʿī (3), Abū Bakr al-Bazzār (4), and al-Khaṭīb’s discussion in al-Kifāyah (5) implies the same—this is the relied-upon view.
The absence of a meeting is established (6) either by the narrator’s own admission or by the firm declaration of a knowledgeable ḥadīth master.
It is insufficient that one of the chains shows an (7) extra transmitter between the two, for that addition may belong to the category of al-mazīd (8). Hence no blanket ruling (9) is given in such a case, since both connection and disconnection remain possible.
On the matter al-Khaṭīb composed a separate work entitled al-Tafsīl li-Mubham (10