An omission from the isnād, if it is made with the intention of suggesting that one heard from a transmitter from whom one did not, is al-mudallas; otherwise it is al-mursal.
The omission in al-mursal may be concealed, in which case it is al-mursal al-khafī; or it may be evident, in which case it is al-mursal al-wāḍiḥ. Concealment and clarity here are relative, varying with the rank of the critic.1
Inferred from al-Khaṭīb's al-Kifāya (p. 476) and elsewhere, and Uṣūl al-Jaṣṣāṣ, 2/61–62. I (the author) say: al-ʿIrāqī supposed that the basis of the distinction between irsāl and tadlīs is contemporaneity (or its absence); his statements on the matter were therefore inconsistent, and his position is contradicted by the irsāl of the mukhaḍramīn, which is not called tadlīs. Al-Ḥāfiẓ supposed that the basis is the meeting itself (or its absence); this position, and al-ʿIrāqī's all the more so, is contradicted by the irsāl of the ṣaḥāba and by al-Bukhārī's irsāl from his teachers, since al-Bukhārī was the furthest of Allāh's creation from tadlīs, as Ibn al-Qayyim said. The correct view is that contemporaneity and meeting are necessary preconditions for the suggestion of audition, since one cannot intend to suggest audition without contemporaneity, but the basis of the distinction is not these themselves. ↩
Al-mursal al-khafī is a mursal whose omission is concealed; clarity and concealment are relative, varying with the rank of the critic.
Al-mursal al-wāḍiḥ is a mursal whose omission is evident; clarity and concealment are relative, varying with the rank of the critic.
Al-mursal is an omission from the end of the isnād, after the tābiʿī; one of the four kinds of rejected report rooted in a break in the chain.
Al-mursal in its broad sense was not rejected by anyone until Imām al-Shāfiʿī; the Ḥanafīs differ over the mursal of the first three generations.
