Sunnah – literally meaning a way or path that is followed – has been used in different contexts in Islamic scholarship. Common Muslims, however, have come to understand it in a limited sense and they often get confused when it is used in varying contexts.

Here is how scholars of different Islamic expertise have used the term:

1. Jurists
Jurists who derive Islamic rulings have used the term Sunnah to distinguish between obligatory and recommended acts of worship. Generally speaking, deeds fall into five categories – Obligatory (Fard/Wajib), Recommended (Sunnah), Permissible (Mubah), Disliked (Makrooh), and Forbidden (Haraam). Jurists use the term Sunnah to describe deeds that are recommended to do but may not be obligatory. It is usually defined as a deed that a person is rewarded if he does, but is not sinful if he leaves it.

However, it must not be used as an excuse to abandon doing the Sunnah. A Muslim is required to adhere to the Sunnah as much as possible.

It is also used in the context of explaining the prohibition of bid’ah – innovation in the religion. That acts of worship must be upon the way – Sunnah – of the Prophet (peace be upon him). Any new acts of worship that are not from the Sunnah and are invented into the religion will be rejected.

2. Islamic legal theorists
Scholars of this specialization (Usool Al-Fiqh) are concerned with the foundations and the principles that form the basis for deriving rulings. In this context, scholars use the word Sunnah to distinguish its status as a primary source of Islamic knowledge along with the Qur’an. The Qur’an and the Sunnah are usually referred together as the sources of Islam pointing to the fact that both are revelations from Allah.

It is often thought that Qur’an alone is the revelation of Allah. It must be known that the commands of the Prophet (peace be upon him) are also solely based on revelation from Allah. In fact, Angel Jibreel would come down to teach the Prophet (peace be upon him) Sunnah just as he would teach him the Qur’an. The evidence for this can be found in the famous Hadith Jibreel. Furthermore, there are several verses and Ahadith that testify to this phenomenon.

3. Scholars of Hadith
Scholars of Hadith are primarily concerned about collecting every piece of information available with regard to the Prophet (peace be upon him). They refer to the term Sunnah in its broadest possible meaning – everything that the Prophet (peace be upon him) said, did, and tacitly approved of, and furthermore his physical characteristics, manners and customs, and biography are all included in the usage of the word Sunnah.

4. Aqeedah specialists
The word Sunnah was also used by scholars of Aqeedah with regard to articles of faith and referring them back to the early generation of Muslims. This was to distinguish between the pure beliefs of the early generation of Muslims and the innovative, false beliefs that swept into later generations.

Ref: Jamaal Al-Din Zarabozo, Authority of Sunnah