Books of mustalah (methodology) speak of a number of classes of hadiths in accordance with their status. The following broad classifications can be made, each of which is to be explained in later articles.
According to the reference to a particular authority, that is, the Prophet (peace and blessings be upon him), a Companion, or a Successor; such hadiths are called marfu` (elevated), mauquf (stopped) and maqtu` (severed) respectively.According to the links in the isnad (chain of transmission), that is, whether the chain of reporters is interrupted or uninterrupted; for example, musnad (supported), muttasil (continuous), munqati` (broken), mu`allaq (hanging), mu`dal (perplexing), and mursal (hurried).According to the number of reporters involved in each stage of the isnad; for example, mutawatir (consecutive) and ahad (isolated), the latter being divided into gharib (scarce, strange), `aziz (rare, strong), and mashhur (famous).According to the manner in which the hadith has been reported, such as using the Arabic words `an (“on the authority of”), haddathana (“he narrated to us”), akhbarana (“he informed us”) or sami`tu (“I heard”). In this category falls the discussion about mudallas (concealed) and musalsal (uniformly-linked) hadiths. In the quotation of isnads in the following series of articles, the first mode of narration mentioned above will be represented with a single broken line thus: —. The three remaining modes of narration mentioned above, which all strongly indicate a clear, direct transmission of the hadith, are represented by a double line thus: ===.According to the nature of the matn (text) and isnad, for example, an addition by a reliable reporter, known as ziyadatu ath-thiqah, or opposition by a lesser authority to a more reliable one, known as shadh (irregular). In some cases, a text containing a vulgar expression, unreasonable remark, or obviously erroneous statement is rejected by the traditionists outright without consideration of the isnad. Such a hadith is known as munkar (denounced). If an expression or statement is proved to be an addition by a reporter to the text, it is declared as mudraj (interpolated).According to a hidden defect found in the isnad or text of a hadith. Although this could be included in some of the previous categories, a hadith mu`allal (defective hadith) is worthy to be explained separately. The defect can be caused in many ways; for example, two types of hadith mu`allal are known as maqlub (overturned) and mudtarib (shaky).According to the reliability and memory of the reporters. The final judgment on a hadith depends crucially on this factor. Verdicts such as sahih (sound), hasan (good), da`if (weak) and maudu` (fabricated, forged) rest mainly upon the nature of the reporters in the isnad.*By Sheikh Suhaib Hassan
* Based on the book: An Introduction to the Science of Hadith, with the author’s kind permission. Excerpted, with some modifications from: