The Problem of Combining Singularity and ḥasan
As for the convergence of singularity (gharābah) and the rank of ḥasan, some raise an objection: since Tirmidhī counts multiplicity of chains (taʿaddud al-turūq) among the conditions for a report to be judged ḥasan, how can a report be both ḥasan and, at the same time, singular?
Reply to the Objection
Scholars reply that Tirmidhī’s requirement of multiple chains for the grade of ḥasan is not unrestricted; it applies only to one subdivision of that category. When he rules that a narration is both ḥasan and singular, he is speaking of a different subdivision.
Some have said that he is alluding to variation among the transmission routes: through one chain the report is singular, while through another it attains the level of ḥasan.
Others contend that the coordinating particle “and” (wa) here carries the sense of “or,” meaning that Tirmidhī was unsure and oscillated between describing the report as singular or as ḥasan, since he could not state the matter conclusively.
A further opinion holds that ḥasan in this context is not meant in its technical sense at all, but rather in its linguistic sense—“something naturally pleasing.” This last view, however, is extremely remote.