Following the Prophet is a divine command.
Linguistically, Sunnah means a way or method that can have two states, either good or bad. It is derived from the word “Sanan”, which is Arabic for: a road or a path.
Sunnah in this sense is mentioned in the hadith of the Messenger of Allah (peace and blessings be upon him) in which he said, “Whosoever does a good Sunnah will get the reward for it and the reward of others who followed him in doing the same thing until the Day of Judgment. And whosoever does a bad Sunnah will have the punishment of doing it and the punishment of others who followed him in practicing it.”(Muslim)
However, the definition of Sunnah differs depending on the area of Shari`ah. For example, a scholar in the area of Usul al-Fiqh (Arabic for: fundamental principles of Islamic jurisprudence) will define Sunnah as “whatever the Prophet was reported to have said, did, or permitted others to do.”
As an example of what he said are the hadiths that deal with the different rulings in different contexts, such as his saying, “The reward of deeds depends on intentions.” (Al-Bukhari and Muslim)
Examples of his actions include the acts of worship, such as the way to perform Prayer, pilgrimage, the etiquette of fasting, etc.
The third type of Sunnah was represented by the Prophet’s silence upon seeing the Companions doing or saying something; his silence in such case served as an approval. Such approval might also be expressed verbally.
An example of his permission is when the Companions had two different opinions during the battle of Bani Qurayzah regarding the Prophet’s command “Do not pray `Asr till you are at Bani Qurayzhah” (Al-Bukhari and Muslim). Some of the Companions understood that the Prophet meant that they should delay Prayer till they reach the place. However, some Companions understood that the Prophet only wanted to urge them to hurry, and so they did pray `Asr on time – before reaching their destination. In neither case did the Prophet say anyone of them was wrong and he did not reject what they did.
Another example of the Prophet’s permission of an action is when Khalid ibn Al-Waleed ate a lizard that he himself refused to eat. Some of the Companions wondered and asked him, “Is it prohibited to eat it, O Messenger of Allah?” The Prophet replied, “No, but it is not common where I live, and I don’t feel like eating it.” (Al-Bukhari and Muslim)
The term Sunnah is also used to refer to a religious ruling that is based on a legal evidence whether from the Qur’an, the Prophet’s sayings, or ijtihad (independent juristic reasoning) by the Companions, such as the collection of the Qur’an in one book and unifying the reading of the Qur’an on one reading narration.
Opposed to Sunnah, there is bid`ah (innovation in religion) about which the Prophet (peace and blessings be upon him) said clearly, “Follow my Sunnah and the Sunnah of the righteous Caliphs after me.” and did not say follow my bid`ah, which should not be taken as the same as Sunnah. This can be shown by the definition used in fiqh where we say this is a sunni divorce (done in accordance with Sunnah) and that is a bid`i divorce (not according to Sunnah).
These differences in looking at Sunnah are dependent on the faculty of scholars, just like any area of science where definitions vary. In general, we can define the Sunnah as whatever the Messenger of Allah (peace and blessings be upon him) said or did to be way of life for us.
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This article has been taken with modifications from onislam.net.