The omission in al-mursal 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 to 62. I (the author) say: ʿAllāmah 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 ṣaḥābah and by Imām al-Bukhārī's irsāl from his teachers, since al-Bukhārī was the furthest of Allāh's creation from tadlīs, as ʿAllāmah 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. The basis is rather the suggestion itself, and there is no necessary connection between it and them, since a man may narrate as mursal from one whom he did meet, while making clear that he did not hear it from him, as when he narrates with the wording "I was told about so-and-so", "it reached me from so-and-so", "a man narrated to me", and the like. But because these formulations were not counted among the marāsīl by the later scholars, it did not occur to al-ʿIrāqī or to Ḥāfiẓ Ibn Ḥajar that the connection is not a necessary one. Reflect on this; and Allāh knows best. See: al-Taqyīd wa-l-Īḍāḥ, pp. 32 and 81; Nukat Ibn Ḥajar, the discussion of tadlīs; Ighāthat al-Lahfān, 1/260. ↩
Al-mursal al-khafī is a mursal whose omission is concealed; clarity and concealment are relative, varying with the rank of the critic.
An omission from the isnād made with the intention of suggesting audition is mudallas; without that intent it is mursal.
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.
An omission from the start of the isnād by the compiler's action is al-muʿallaq, one of the four kinds of rejected report rooted in a break in the chain.