Q: How did the four Madh-habs (Schools of Jurisprudence) come to existence? And how did the Four Imams allow Ijtihad for themselves and prohibit it for others? What is the evidence on the permissibility of following only one of the Four Madh-habs?

A: All Praise is due to Allah Alone and peace and blessings be upon His Messenger, his family and Companions. To proceed: There are a lot of jurists who practiced Ijtihad, especially in the first three generations which the Messenger (peace be upon him) described to be the best of all generations. The most famous ones were four jurists: Abu Hanifah Al-Nu`man ibn Thabit in Iraq, (Part No. 5; Page No. 56)  Abu `Abdullah Malik ibn Anas Al-Asbahy in Al-Madinah Al-Munawwarah, Abu `Abdullah Muhammad ibn Idris Al-Shafi`y Al-Qurashy, the scholar of Quraysh and source of pride in Baghdad, then Egypt and Abu `Abdullah Ahmad ibn Muhammad ibn Hanbal Al-Shaibany, Imam of scholars of Hadith, the highest example and best Faqih in Iraq during his lifetime.There are many reasons behind their being well known, such as: The spread of their Madh-habs in the country where they were either brought up or traveled to according to Allah's will. As in the case of Abu Hanifah and Ahmad (may Allah be merciful to them) in Iraq, Malik in Al-Madinah, and Al-Shafi`y in Makkah and Egypt. Another reason may be the role played by their disciples and everyone who followed their Madh-hab, and acted upon their opinions and Ijtihad in spreading their Madh-hab either in their home countries or in the countries they traveled to. Such disciples include Muhammad ibn Al-Hasan and Abu Yusuf in Iraq, Ibn Al-Qasim and Ash-hab in Egypt. Sahnun in Morocco, Al-Rabi` ibn Sulayman in Egypt, and the disciples of Imam Ahmad in the Levant (the region covering Syria, Lebanon, Jordan, and Palestine) and Iraq and other countries. These reasons may also include the ruler's adoption of the opinions of a particular Madh-hab, following its scholars, and putting them in positions pertaining to judicial authorities and Ifta', and opening schools for teaching their Madh-hab and providing them with honorable means of life through allocated endowments and a means of life.None of the Four Imams called people to follow their Madh-hab (School of Jurisprudence), or obliged anyone else to act in accordance with it or with a specific Madh-hab. They used to call people to follow the Qur'an and the Sunnah, interpret Islamic texts, set up the basic principles and discuss minor issues according to general guidelines. They also used to issue Fatwas concerning what people asked them about and substantiated their Fatwas with evidence from the Qur'an and Sunnah. However, they did not oblige any of their students or anyone else to follow their views. They criticized those who did so and said that their opinions should be cast aside if they went against an authentic Hadith. One of them said: If the Hadith is Sahih then this is (Part No. 5; Page No. 57) my Madh-hab. May Allah have mercy on them all!Therefore, it is not obligatory upon everyone to follow a particular Madh-hab, one should do his best to learn the truth for himself if possible. He should seek the help of Allah in doing so, then rely on the legacy that the earlier Muslim scholars left behind for those who came after them, through which they made it easier to understand and apply the texts. Whoever can not derive rulings and deduce them from the texts for any reason that prevents him from doing so, should ask trustworthy scholars for whatever rulings of Shari`ah (Islamic law) they need, for Allah (Exalted be He) says: So ask the people of the Scripture, if you do not know. So, one should do his best to ask one whom he trusts among those who are well known for their knowledge, virtue, piety and righteousness.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.