Ṣaḥīḥ and ḥasan are accepted in every case; ḍaʿīf is not accepted except in faḍāʾil and targhīb / tarhīb. Ibn Ḥajar's three conditions for accepting a weak ḥadīth in faḍāʾil.
If any one of the attributes of the ṣaḥīḥ or the ḥasan is missing, the ḥadīth is ḍaʿīf (literally, weak).
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.
