• "Imam (leader), Hafiz (preserver)."
• "Reliable, trustworthy."
• "Makes mistakes."
• "Weak."
• "Abandoned (by the traditionists)."
• "Liar, used to fabricate ahadith."

Reporters who have been unanimously described by statements such as the first two may contribute to a Sahih ("sound", see later) isnad. An isnad containing a reporter who is described by the last two statements is likely to be Da`if jiddan (very weak) or Maudu` (fabricated). Reporters who are the subject of statements such as the middle two above will cause the isnad to be Da`if (weak), although several of them relating the same hadith independently will often increase the rank of the hadith to the level of Hasan (good). If the remarks about a particular reporter conflict, a careful verdict has to be arrived at after in-depth analysis of e.g., the reason given for any disparagement, the weight of each type of criticism, the relative strictness or leniency of each critic, etc.

The earliest remarks cited in the books of Rijal go back to a host of Successors, followed by those after them until the period of the six canonical traditionists, a period covering the first three centuries of Islam. A list of such names is provided by the author in his thesis, Criticism Of Hadith Among Muslims With Reference To Sunan Ibn Majah, at the end of chapters IV, V and VI.

Among the earliest available works in this field are Ta'rikh of Ibn Ma`in (d. 233), Tabaqat of Khalifa b. Khayyat (d. 240), Ta'rikh of al-Bukhari (d. 256), Kitab al-Jarh wa 'l-Ta'dil of Ibn Abi Hatim (d. 327) and Tabaqat of Muhammad b. Sa'd (d. 320).

A number of traditionists made efforts specifically for the gathering of information about the reporters of the five famous collections of hadith, those of al-Bukhari (d. 256), Muslim (d. 261), Abu Dawud (d. 275), al-Tirmidhi (d. 279) and al-Nasa'i (d. 303), giving authenticating and disparaging remarks in detail. The first major such work to include also the reporters of Ibn Majah (d. 273) is the ten-volume collection of al-Hafiz `Abd al-Ghani al-Maqdisi (d. 600), known as Al-Kamal fi Asma' al-Rijal. Later, Jamal al-Din Abu 'l-Hajjaj Yusuf b. `Abd al-Rahman al-Mizzi (d. 742) prepared an edited and abridged version of this work, punctuated by places and countries of origin of the reporters; he named it Tahdhib al-Kamal fi Asma' al-Rijal and produced it in twelve volumes. Further, one of al-Mizzi's gifted pupils, Shams al-Din Abu `Abdullah Muhammad b. Ahmad b. `Uthman b. Qa'imaz al-Dhahabi (d. 748), summarised his Shaikh's work and produced two abridgements: a longer one called Tahdhib al-Tahdhib and a shorter one called Al-Kashif fi Asma' Rijal al-Kutub al-Sittah.

A similar effort with the work of al-Mizzi was made by Ibn Hajar (d. 852), who prepared a lengthy but abridged version, with about one-third of the original omitted, entitled Tahdhib al-Tahdhib in twelve shorter volumes. Later, he abridged this further to a relatively-humble two- volume work called Taqrib al-Tahdhib.

The work of al-Dhahabi was not left unedited; al-Khazraji (Safi al-Din Ahmad b. `Abdullah, d. after 923) summarised it and also made valuable additions, producing his Khulasah.

A number of similar works deal with either trustworthy reporters only, e.g. Kitab al-Thiqat by al-`Ijli (d. 261) and Tadhkirah al-Huffaz by al-Dhahabi, or with disparaged authorities only, e.g. Kitab al-Du`afa' wa al-Matrukin by al-Nasa'i and Kitab al-Majruhin by Muhammad b. Hibban al-Busti (d. 354).

Two more works in this field which include a large number of reporters, both authenticated and disparaged, are Mizan al-I'tidal of al-Dhahabi and Lisan al-Mizan of Ibn Hajar.