Con el paso del tiempo, cada isnad incluyó a más transmisores, por lo que la situación exigió una disciplina estricta en la aceptación de los ahadith; las reglas que regulan esta disciplina se conocen como Mustalah al-Hadith (la Clasificación del Hadiz).

As time passed, more reporters were involved in each isnad, and so the situation demanded strict discipline in the acceptance of ahadith; the rules regulating this discipline are known as Mustalah al-Hadith (the Classification of Hadith).

Entre los primeros hadiziztas (muhaddithin, eruditos del Hadiz), las reglas y criterios que regían su estudio del Hadiz eran meticulosos, pero parte de su terminología variaba de una persona a otra. Sus principios comenzaron a ponerse por escrito de forma sistemática, aunque dispersos en diversos libros, por ejemplo en Al-Risalah de al-Shafi'i (m. 204), en la Introducción al Sahih de Muslim (m. 261) y en el Yami' de al-Tirmidhi (m. 279). Muchos de los criterios de los primeros hadiziztas, por ejemplo al-Bujari, fueron deducidos por eruditos posteriores a partir de un estudio cuidadoso de qué transmisores o isnads eran aceptados y cuáles rechazados por ellos.

Amongst the early traditionists (muhaddithin, scholars of Hadith), the rules and criteria governing their study of Hadith were meticulous but some of their terminology varied from person to person, and their principles began to be systematically written down, but scattered amongst various books, e.g. in Al-Risalah of al- Shafi'i (d. 204), the Introduction to the Sahih of Muslim (d. 261) and the Jami' of al-Tirmidhi (d. 279); many of the criteria of early traditionists, e.g. al-Bukhari, were deduced by later scholars from a careful study of which reporters or isnads were accepted and rejected by them.

Una de las primeras obras que intentaron abarcar el Mustalah de manera exhaustiva, utilizando la terminología estándar (es decir, generalmente aceptada), fue la de al-Ramahurmuzi (m. 360). La siguiente contribución importante fue Ma'rifah 'Ulum al-Hadith, de al-Hakim (m. 405), que abarcaba cincuenta clasificaciones del Hadiz, pero aún dejaba algunos puntos sin tratar; Abu Nu'aim al-Isbahani (m. 430) completó algunas de las partes que faltaban en esta obra. Después llegó Al-Kifayah fi 'Ilm al-Riwayah, de al-Khatib al-Baghdadi (m. 463), y otra obra sobre la manera de enseñar y estudiar el Hadiz; se consideró que los eruditos posteriores estaban en gran deuda con la obra de al-Khatib.

One of the earliest writings to attempt to cover Mustalah comprehensively, using standard (i.e. generally-accepted) terminology, was the work by al-Ramahurmuzi (d. 360). The next major contribution was Ma'rifah 'Ulum al-Hadith by al- Hakim (d. 405), which covered fifty classifications of Hadith, but still left some points untouched; Abu Nu'aim al-Isbahani (d. 430) completed some of the missing parts to this work. After that came Al-Kifayah fi 'Ilm al- Riwayah of al-Khatib al-Baghdadi (d. 463) and another work on the manner of teaching and studying Hadith; later scholars were considered to be greatly indebted to al-Khatib's work.

Tras las aportaciones posteriores de Qadi 'Iyad al-Yahsubi (m. 544) y Abu Hafs al-Mayanji (m. 580), entre otros, surgió la obra que, aunque modesta en extensión, era tan completa en su excelente tratamiento de la materia que llegó a ser la referencia estándar para miles de eruditos y estudiantes del Hadiz durante muchos siglos, hasta la actualidad: 'Ulum al-Hadith de Abu 'Amr 'Uthman Ibn al-Salah (m. 643), conocida comúnmente como Muqaddimah Ibn al-Salah, compuesta mientras enseñaba en el Dar al-Hadith de varias ciudades de Siria. Algunas de las numerosas obras posteriores basadas en la de Ibn al-Salah son:

After further contributions by Qadi 'Iyad al- Yahsubi (d. 544) and Abu Hafs al-Mayanji (d. 580) among others, came the work which, although modest in size, was so comprehensive in its excellent treatment of the subject that it came to be the standard reference for thousands of scholars and students of Hadith to come, over many centuries until the present day: 'Ulum al- Hadith of Abu 'Amr 'Uthman Ibn al-Salah (d. 643), commonly known as Muqaddimah Ibn al-Salah, compiled while he taught in the Dar al-Hadith of several cities in Syria. Some of the numerous later works based on that of Ibn al-Salah are:

• Un resumen de la Muqaddimah, Al-Irshad de al-Nawawi (m. 676), que más tarde condensó en su Taqrib; al-Suyuti (m. 911) compiló un valioso comentario sobre este último titulado Tadrib al-Rawi.

• An abridgement of Muqaddimah, Al-Irshad by al- Nawawi (d. 676), which he later summarised in his Taqrib; al-Suyuti (d. 911) compiled a valuable commentary on the latter entitled Tadrib al-Rawi.

• Ikhtisar 'Ulum al-Hadith de Ibn Kathir (m. 774), Al-Julasah de al-Tibi (m. 743), Al-Minhal de Badr al-Din b. Yama'ah (m. 733), Al-Muqni' de Ibn al-Mulaqqin (m. 802) y Mahasin al-Istilah de al-Balqini (m. 805), todos los cuales son compendios de la Muqaddimah de Ibn al-Salah.

• Ikhtisar 'Ulum al-Hadith of Ibn Kathir (d. 774), Al-Khulasah of al-Tibi (d. 743), Al- Minhal of Badr al-Din b. Jama'ah (d. 733), Al- Muqni' of Ibn al-Mulaqqin (d. 802) and Mahasin al-Istilah of al-Balqini (d. 805), all of which are abridgements of Muqaddimah Ibn al- Salah.

• Al-Nukat de al-Zarkashi (m. 794), Al-Taqyid wa 'l-Idah de al-'Iraqi (m. 806) y Al-Nukat de Ibn Hajar al-'Asqalani (m. 852), todos ellos notas adicionales sobre los puntos expuestos por Ibn al-Salah.

• Al-Nukat of al-Zarkashi (d. 794), Al-Taqyid wa 'l-Idah of al-'Iraqi (d. 806) and Al-Nukat of Ibn Hajar al-'Asqalani (d. 852), all of which are further notes on the points made by Ibn al- Salah.

• Alfiyyah al-Hadith de al-'Iraqi, una reelaboración de al-Muqaddimah en forma de extenso poema, que fue objeto de varios comentarios, entre ellos dos (uno extenso y otro breve) escritos por el propio autor; Fath al-Mughith de al-Sakhawi (m. 903); Qatar al-Durar de al-Suyuti; y Fath al-Baqi del Shaykh Zakariyyah al-Ansari (m. 928).

• Alfiyyah al-Hadith of al-'Iraqi, a rewriting of Muqaddimah in the form of a lengthy poem, which became the subject of several commentaries, including two (one long, one short) by the author himself, Fath al-Mughith of al-Sakhawi (d. 903), Qatar al-Durar of al- Suyuti and Fath al-Baqi of Shaykh Zakariyyah al-Ansari (d. 928).

• Al-Iqtirah de Ibn Daqiq al-'Id (m. 702). Tanqih al-Anzar de Muhammad b. Ibrahim al-Wazir (m. 840), objeto de un comentario de al-Amir al-San'ani (m. 1182).

• Al-Iqtirah of Ibn Daqiq al-'Id (d. 702). Tanqih al-Anzar of Muhammad b. Ibrahim al- Wazir (d. 840), the subject of a commentary by al-Amir al-San'ani (d. 1182).

• Nujbat al-Fikr de Ibn Hayar al-'Asqalani, nuevamente objeto de varios comentarios, entre ellos uno del propio autor, otro de su hijo Muhammad, y los de 'Ali al-Qari (m. 1014), 'Abd al-Ra'uf al-Munawi (m. 1031) y Muhammad b. 'Abd al-Hadi al-Sindi (m. 1138). Entre quienes reformularon la Nujbah en forma poética se encuentran al-Tufi (m. 893) y al-Amir al-San'ani.

• Nukhbah al-Fikr of Ibn Hajar al-'Asqalani, again the subject of several commentaries, including one by the author himself, one by his son Muhammad, and those of 'Ali al-Qari (d. 1014), 'Abd al-Ra'uf al-Munawi (d. 1031) and Muhammad b. 'Abd al-Hadi al-Sindi (d. 1138). Among those who rephrased the Nukhbah in poetic form are al-Tufi (d. 893) and al- Amir al-San'ani.

• Alfiyyah al-Hadith de al-Suyuti, la obra poética más completa en el campo. Al-Manzumah de al-Baiquni, que fue ampliada, entre otros, por al-Zurqani (m. 1122) y Nawab Siddiq Hasan Khan (m. 1307). Qawa'id al-Tahdith de Jamal al-Din al-Qasimi (m. 1332).

• Alfiyyah al-Hadith of al-Suyuti, the most comprehensive poetic work in the field. Al-Manzumah of al-Baiquni, which was expanded upon by, amongst others, al-Zurqani (d. 1122) and Nawab Siddiq Hasan Khan (d. 1307). Qawa'id al-Tahdith of Jamal al-Din al-Qasimi (d. 1332).

• *Taujih al-Nazar* de Tahir al-Jaza'iri (m. 1338), un resumen de la *Ma'rifah* de al-Hakim.

• Taujih al-Nazar of Tahir al-Jaza'iri (d. 1338), a summary of al-Hakim's Ma'rifah.