Dr. Muzzamil Siddiqi, former president of the Islamic Society of North America (ISNA), states the following: “Originally, we are commanded to obey Allah’s commands expressed in the Qur’an and in the Sunnah. The early generations of Islam used to abide by these two sources. After the third century A.H. people started categorizing themselves to different schools and sects.
In this case, we are to follow the Qur’an and the Sunnah; it is accessible for any Muslim who wants to know the truth.
These schools are the Islamic schools of Jurisprudence. During the time of the Prophet, peace and blessings be upon him, his Companions, may Allah be pleased with them all, would go to him whenever they had a question and he would answer them. After the demise of the Prophet, peace and blessings be upon him, they used to go to the Rightly- Guided Caliphs, may Allah be pleased with them, and other prominent Companions to answer their questions.
When Islam spread in other lands of the Near East and many more people entered into the fold of Islam, there were many questions that came from different sides, so we had a group of scholars who took it upon themselves to study the Qur’an and the Sunnah and answer people’s questions.
There were some who became very prominent and well-known and had a large number of students. These students carried on the methodology of their teachers in answering Islamic questions. Thus, came these schools of Fiqh.
There were many schools, but then slowly they all merged into four main schools among the Sunni’s.
Nowadays, most of the Muslims follow one of these four schools and there are also some who do not restrict themselves to any one of them.
Differences among these schools are based upon their methodologies in their interpretation of the Qur’an and Sunnah, but in most cases, the differences are minor. There has been a great deal of rapprochement and interaction within the scholars of these four schools.”