An accepted report, if it is free of any other accepted report contradicting it, even apparent contradiction, is al-muḥkam (literally, firmly established).
If another accepted report contradicts it, it is mukhtalaf al-ḥadīth.1
Mukhtalaf al-ḥadīth refers to a contradiction between two aḥādīth. Mushkil al-ḥadīth, by contrast, refers to an accepted ḥadīth that contradicts another piece of evidence, such as the Qurʾān or the ijmāʿ of the Companions. Some scholars treat the two terms as synonymous. When a ḍaʿīf narration runs counter to a ṣaḥīḥ or ḥasan one, that too is sometimes called mukhtalaf al-ḥadīth. [tr.] An example: the ḥadīth "There is no contagion and no evil omen," alongside the ḥadīth "Flee from the leper as you flee from the lion." Their outward sense suggests contradiction. Sharḥ al-Nukhba, p. 44. ↩
If any one of the attributes of the ṣaḥīḥ or the ḥasan is missing, the ḥadīth is ḍaʿīf (literally, weak).
If the narrators of a ḥadīth agree in their wording of transmission, in any verbal feature, in an action or in some shared quality, this is al-musalsal (a chained or serial ḥadīth).
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).
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).
