It is to be known, that the tradition among the Shiâhs of the _Imámiyat-âsulín_ sect is divided into four parts: _sáhíh_, “authentic;” _hasen_, “elegant;” _músik_, “strong;” and _sâíf_, “weak.”
An _hadís sahih_, “an authentic tradition,” is one, the authority of which goes back to _mâsúm_,[580] according to the narration of an _âdil Imám_, “a just Imám,” in the description of whom the _árbáb-i-hadis_, “the masters of history,” have used the word _âdil_, whether the narrator be one person, or whether there be more than one, provided in the description of them all the same language has been used.
An _hadis hasen_, “an elegant tradition,” is one, the authority of which goes back, like that of the _hadis sahih_, to the _mâsúm_; but, according to the narrative of a venerable Imám, in this way, that although, in regard to the narrator of it, the words _sikah âdíl_, “trusty and just,” have not come down to us from the historians, yet they have praised him in other words.
An _hadis músik_, “a strong tradition,” is that, in the description of whose narrators the words _sikah âdil_ have been used by the historians, but some or all of the narrators of which are not _Imámís_, “followers of Ali.”
An _hadis sâíf_, “a weak tradition,” is that in which none of these three conditions are found; viz.: 1st, the inference from the commendation of _sikah âdil_; 2nd, a praise other than these two words; and 3rd, the qualification _sikah âdil_, with erroneous belief on the part of the narrator.
A tradition is either _in regular succession_, or _not in regular succession_. A tradition is in regular succession, when a great multitude on the authority of a great multitude make the same narration, until it reaches to the _mâsúm_, in such a manner, that the number of each multitude, in each particular age, shall have been so great as to exclude the idea of their having combined in telling a lie. A tradition is without a regular succession, when the number of narrators does not, in all or several stages, reach to that multitude, as before said, and this kind of tradition is called, in the peculiar idiom of the masters of history, _the information of one_. Among the Akhbarians, there is no such arrangement and classification of evidence, and God knows the truth.