Al-qarīnān: if two men are of the same age and have met the same teachers, they are qarīnān (peers).
Riwāyat al-aqrān: the narration of one of two peers from the other is riwāyat al-aqrān.1
An example: the narration of Zāʾida ibn Qudāma from Zuhayr ibn Muʿāwiya, while no narration in the reverse direction, from Zuhayr from Zāʾida, is known. ↩
When each of two peers narrates from the other, this is al-mudabbaj (literally, embellished or paired); al-ʿIrāqī, following al-Dāraquṭnī, did not require the two narrators to be peers.
An omission of two or more consecutive narrators at any point in the chain is al-muʿḍal, one of the four kinds of rejected report rooted in a break in the chain.
When the routes of a ḥasan li-dhātihi narration multiply, the ḥadīth is upgraded to al-ṣaḥīḥ li-ghayrihi (the sound by virtue of something other than itself).
Al-Shāfiʿī accepts the mursal under three conditions; some Shāfiʿīs treat the third as one of the four corroborating supports, leaving two conditions.
