Saboda wannan, mazhabobi da ra'ayoyi ba su zama guda ɗaya ba, kuma ijtihadi da ra'yi sun kasance a hannun mutane wajen karɓar hukuncin da suka ga daidai ne. Zaɓi kuma ya kasance ga alƙalai da sarakuna su yi hukunci da abin da suka ga ya dace. Saboda haka kowane imam na fiqhu yana da ɗalibai waɗanda suka zo suna nazarin ra'ayoyinsa, suna bayyana mazhabarsa, kuma kallon da ake yi wa wannan saɓani da ya faru ya canja, ya zama ilimi mai zaman kansa, suka kira shi ilmin saɓani (‘ilm al-khilaf). Sun yi nazarinsa kamar yadda suke nazarin usul al-fiqh. Sun ce saɓanin malamai rahama ne. Ɗalibin kowane imam yana yin faɗaɗa a cikin furu'i (rassan fiqhu). Wannan faɗaɗawa ce ta adana mazhabobin wasu mujtahidai, kuma ita ce dalilin ɓacewar wasu.
Al-Awza'i, al-Hasan al-Basri, al-Thawri da Ibn Jarir al-Tabari suna cikin manyan malamai dangane da faɗin ilimi da ijtihadi. Duk da haka ba su faɗaɗa a furu'i ba, sun takaita kansu ga usul, kuma ba su da ɗalibai da za su yi bayanin matsayin mazhabarsu, shi ya sa ba a aiki da su ba, kuma ba su yaɗu ba. Sauran imamai kamar Abu Hanifa, Ja'far al-Sadiq, Zaid ibn al-Husain, al-Shafi'i, Ahmad ibn Hanbal da Malik, suna da ɗalibai da mabiya, don haka an rubuta mazhabobinsu kuma suka ci gaba da wanzuwa.
Duk da takurawar da Abu Ja'far al-Mansur ya sanya wa Ja'far al-Sadiq da sauran mutanen gidan ‘Ali, ya yi ƙididdigar hukunce-hukunce kuma yana da ɗalibai daga Shi'a da sauransu. Sun rubuta ra'ayoyinsa, suna ɗaukar su kamar wani abu mai kama da Sunna. Mazhabarsa ta yaɗu a yankuna da dama na duniya.
Abu Hanifa yana da ɗalibai da yawa, waɗanda aka fi sani da su sune Abu Yusuf, Muhammad ibn al-Hasan al-Shaibani da Zufar. Dukansu mujtahidai ne kamar Abu Hanifa. Ko da yake sun haɗa ra'ayoyinsu da nasa, ana yaba musu saboda rubuta mazhabar Abu Hanifa. Haka ma abin yake ga Imam Malik. Ya zauna a Madina; yana da ɗalibai da yawa waɗanda suka shahara sosai wajen bincike da tace hadisi da masu ruwaito hadisi, musamman dangane da littafin al-Muwatta. Ɗalibansa bayansa sun kasance suna rubuta fatawoyinsa, suna faɗaɗa bayanin furu'i, kuma suna bayyana ra'ayoyinsu kan al'amura. Duk da shaharar Malik, lada na yaɗuwar mazhabarsa yana zuwa ga ɗalibansa.
Dangane da al-Shafi'i kuwa, ya kafa shahararsa da hannunsa a fagen usulul fiqhi, kamar yadda ya bayyana a cikin babban littafinsa al-Umm, wanda tare da al-Risala da Ibtalul Istihsan, su ne manyan misalan farkawar hankali a wannan zamani. Ɗalibansa, kamar al-Rabi'i da al-Muzni, waɗanda suka bi wannan hanya, suka yi nazari a kan ra'ayoyinsa, suka faɗaɗa mazhabarsa, har ta yaɗu ko'ina.
Haka kuma ga Ahmad ibn Hanbal, duk da cewa hadisi ya fi mamaye mazhabarsa, yana da ɗalibai da suka faɗaɗa mazhabarsa a gare shi, suka yi nazari a kan ra'ayoyinsa. Lada yana zuwa da farko ga waɗannan ɗalibai, ba wai kawai saboda yaɗa mazhabar malamansu da imamansu ba, har ma saboda bayyana fiqhi da tabbatar da cewa ya bunƙasa, har zamaninsu ya zama mafi haske fiye da zamanin imamai. Domin a wannan zamani ne aka yi sharhin hukunce-hukunce da bayyana dalilai, ta haka malaman fiqhi suka himmatu wajen nazarin fiqhi da bayyana shi, musamman ilimin usulul fiqhi, wanda shi ne tushen fiqhi na gaskiya. Yanayin fiqhi ya ci gaba da yaɗuwa har ya bunƙasa sosai. Kololuwar bunƙasarsa ta kasance a ƙarni na huɗu bayan Hijira, shekara ɗari bayan an kafa mazhabobin.
Owing to this, the mazhabs and opinions were not unified and Ijtihād and ra’i remained with the people in adopting the hukm they deemed correct. And the choice remained for judges and rulers to judge with what they deemed as appropriate. Due to this each imam of fiqh has students who came to study their opinions and explain his mazhab and the outlook towards this disagreement which took place changed and it became a science in its own right, they called it the science of disagreement (‘ilm al-khilaf). They studied it just as they studied usul al-fiqh. They said that the disagreement of the imams was a mercy. The student of each imam used to expand on the furu’ (branches of fiqh). It was this expansion which preserved the mazhabs of certain mujtahidin and was the reason for the extinction of others. Al-Awza’i, al-Hasan al-Basri, al-Thawri and Ibn Jarir al-Tabari are some of the greatest imams in terms of their breadth of knowledge and Ijtihād. However they did not expand in furu’ rather confined themselves to the usul and they did not have students who would expound the position of their mazhab, that is why they were not acted upon and they did not spread. As for the rest of the imams such as Abu Hanifah, Ja’far al-Sadiq, Zayd ibn al-Husayn, al-Shafi’i, Ahmad ibn Hanbal and Malik, they had students and followers, so their mazhabs were recorded and continued to exist. Despite the restrictions imposed by Abu Ja’far al-Mansur on Ja’far al-Sadiq and others from the family of ‘Ali he deduced rules and he had students from the Shi’a and others. They recorded his opinions and looked upon them as something akin to the Sunnah. His mazhab spread in many regions of the world. Abu Hanifah used to have many students, the most well known are Abu Yusuf, Muhammad ibn al-Hasan al Shaybani and Zufar. They were all mujtahids like Abu Hanifah. Although they mixed their opinions with his, the credit goes to them for recording the mazhab of Abu Hanifah. The same goes for Imam Malik. He used to reside in Madinah; he had many students who were widely known for scrutinising the hadīth and transmitters of hadīth, especially in regard to the book al Muwatta. His students after him used to record his fatwas and expand on the furu’ and give their views on issues. Despite Malik’s fame the credit for spreading his mazhab goes to his students. As for al-Shafi’i he had established his towering fame by his own hands in usul al-fiqh which is indicated by what comes in the large work al-Umm which along with al-Risala and Ibtal al-Istihsan are the greatest samples of intellectual awakening in that age. His students, such as al-Rabi’ and al-Muzni who proceeded according this method and studied his opinions and expanded his mazhab and so it spread far and wide. Similarly for Ahmad ibn Hanbal, despite the dominant prevalence of hadīth in his mazhab, he had students who expanded his mazhab for him and studied his opinions. The credit first and foremost goes to those students, not only for spreading the mazhab of their teachers and imams but also for the exposition of the fiqh and ensuring that it flourished until their age was considered more radiant than the age of the imams. Since it was in this age that the commentaries of ahkām and clarification of evidences took place, in this way the fuqaha rushed ahead in studying fiqh and explaining it especially the science of usul al-fiqh which is the true basis of fiqh. The situation of fiqh continued to spread until it flourished greatly. The pinnacle of its bloom was in the fourth century A.H, a century after the mazhabs were formed
