The primary sources of knowledge about Islam are the Qur’an, which Muslims generally believe is the divinely revealed word of God, and the Sunnah, which refers to the example or precedent of the Prophet Muhammad (i.e., what he said, did, approved, disapproved, caused, ordered, or allowed to happen). Much of what is known about the Sunnah is from the collection of sayings or reports known as hadith, or prophetic tradition. The hadith describe actions of the Prophet Muhammad or actions that his companions attributed to his teachings. Hadith also elaborate and provide context to the Qur’an.
For Shi’as, in addition to the aforementioned, the rulings of the twelve Imams are considered a primary source. Other sources may exist for different Muslim sects.
In addition to these primary sources, Muslims have also traditionally relied on the following: scholarly consensus, that is, the agreement of knowledgeable scholars upon a particular issue; and analogical reasoning, which means applying principles or laws derived from the Qur’an and Sunnah to similar situations not explicitly addressed by them. The lived experience of Islam, which naturally varies widely not only in different cultures but also with different individuals, also impacts and determines a Muslim’s understanding and practice of Islam.