The people involved in the transmission of a hadeeth constitute its isnad.  The isnad informs us about the hadeeth’s source, and this information later became an essential part of the hadeeth (Azami 31).  Abdullah b. Al-Mubarak, one of the teachers of al-Bukhari, is reported to have said, “The isnad is part of the religion: had it not been for the isnad, whoever wished to would have said whatever he liked” (Hasan 11)[1].  There is some indication that the isnad was used before the first tribulation, though it was not until the end of the first century of the Hijrah that it was fully developed (Azami 33).  (However, John Burton in his An Introduction to the Hadith says that the isnad did not yet exist in the first century) The other part of the hadeeth that actually contains the specific saying or action of the Prophet, may the mercy and blessings of God be upon him, is its matn or text.

For the classification of hadeeth, there are several broad categories, of which only seven will be very briefly discussed here.  The seven categories are classifications according to 1) the reference to a particular authority, 2) the links in the isnad, 3) the number of reporters involved in each stage of the isnad, 4) the technique used in reporting the hadeeth, 5) the nature of the isnad and matn, 6) a hidden defect found in the hadeeth’s isnad or matn, and 7) the reliability and memory of the reporters (Hasan 14-16).

The first category, classification according to the reference to a particular authority, pertains to whether it goes back to the Prophet, a Companion, or a Successor.  A marfu’ or “elevated” narration is one that back to the Prophet, and this is regarded as the best grade (Burton 112).  A mawqoof or “stopped” narration is one that goes back to a Companion, while a maqtu’ or “severed” narration is one that goes back to a Successor.  This classification is significant in that it differentiates between the Prophet’s sayings and actions and that of a Companion or Successor.

The second category, classification according to the links in the isnad, makes several different distinctions.  The musnad or “supported” hadeeth is the best out of the group as it contains no break in the chain of authorities reporting the hadeeth back to the Prophet (Burton 111).  The mursal or “unattached” hadeeth is one that contains a gap of one generation (according to both Azami and Hasan it is a hadeeth reported by a Successor who drops the Companion from whom he learned it in the isnad).  The munqati’ or “broken” hadeeth is one which is missing a link closer to the traditionalist reporting it (i.e., before the Successor).  This applies even if there appears to be no break in the chain, if it is known that one of the reporters could not have heard hadeeth from the immediate authority given in the isnad, even if they are contemporaries.  The term munqati’ also is used by some scholars to refer to a hadeeth in which a reporter does not name his authority and instead says, “a man narrated to me” (Hasan 22).  A hadeeth is mu’dal or “perplexing” if more than one consecutive reporter is missing in the isnad.  If the isnad is dropped altogether and the reporter directly quotes the Prophet, then the hadeeth is considered mu’allaq or “hanging” (Hassan 22).

Within the third category, hadeeth are classified according to how many reporters are in each stage of the isnad, i.e. in each generation of reporters.  The two main classifications are mutawatir (“consecutive”) and ahad (“single”), though ahad is further divided into many subdivisions, among them ghareeb (“scarce” or “strange”), ‘azeez (“rare” or “strong”), and mash’hoor (“famous”).  A mutawatir hadeeth is one that is reported by a large number of people whose agreement upon a lie is not reasonably possible and in which the possibility of coincidence is negligible.  The minimum number of required reporters differs among the scholars of hadeeth, and ranges from four to several hundred (Azami 43).  The hadeeth may be mutawatir in either meaning or words, the former being the more common one.  Al-Ghazali stipulated that the hadeeth must be mutawatir in the beginning, middle, and last stages of its isnad (Hasan 30).  A hadeeth that is ahad is one whose number of reporters does not come near to that required for a mutawatir hadeeth.  A hadeeth is classified as ghareeb if at any stage (or every stage) in the isnad there is only one person reporting it.  A hadeeth is classified as ‘azeez if at every stage in the isnad there are at least two people reporting it.  If at least three people report a hadeeth in every stage of its isnad, then it is classified as mash’hoor, although the term is also applied to those hadeeth which start out as ghareeb or ‘azeez but then end up with a larger number of reporters (Hasan 32).

In the fourth category, hadeeth are classified according to manner in which they are reported.  As was mentioned earlier, there is a corresponding special term to denote a particular mode of learning or transmission when a student or scholar learned a hadeeth.  “Haddathana,” “akhbarana,” and “sami’tu” all indicate that the reporter personally heard the hadeeth from his own sheikh.  “‘An” and “qaala” are more vague and can signify either hearing from the sheikh in person or through someone else.  Actually, “‘an” is very inferior and can signify learning the hadeeth through any one of various modes of transmission (Azami 22).  A hadeeth can be labeled as weak due to the uncertainty caused by using the latter two terms, which respectively translate into “on the authority of” and “he said” (Hasan 33).  One who practices tadlees, “concealing”, reports from his sheikh that which he did not hear from him, or reports from a contemporary whom he never met.  This violates the principle that a hadeeth must be heard first-hand in order to be transmitted (Burton 112).  Another type of tadlees, which is considered the worst among them, is when a reliable scholar reports from a weak authority who is in turn reporting from a reliable scholar.  The person who is reporting this isnad may show that he heard it from his sheikh, but then omits the weak authority and simply uses the term “‘an” to link his sheikh with the next trustworthy one in the isnad (Hasan 34).

If throughout the isnad all the reporters (including the Prophet) use the same mode of transmission, repeat an additional statement or remark, or act in a particular way while narrating the hadeeth, then it is called musalsal (“uniformly-linked”).  This type of knowledge is useful for discounting the possibility of tadlees in a particular hadeeth (Hassan 35).