Hadith: Collections of sayings and teachings of Muhammad (and Ahl al-Bayt for Shia Muslims)

In English, the word hadith is also used as the plural word for a group of these narrations, although the plural in Arabic is a-HAA-deeth.

For most self-identified Muslims, hadiths are used along with the Qur'an to interpret Sharia. Sunnis follow the Kutub al-Sittah; Shias follow the Kutub al-Arba'a; Ibadis follow Tartib al-Musnad. Hadiths attributed to Abu Hurairah are the most common hadiths in Sunnism. Unlike the Qur'an, hadiths are not universally accepted by Muslims; some Muslims claim that most hadiths are fabrications (pseudepigrapha) created in the 8th and 9th century AD, and which are falsely attributed to Muhammad.

The word hadith means something new or a piece of information. The religious meaning of hadith is a statement, action or approval attributed to the prophet of Islam, Muhammad. Therefore, hadith can be divided into three categories based upon their content:

1. An attributed statement of the Prophet
2. An attributed action of the Prophet
3. An attribution of the Prophet’s approval of an action done by other than him

After Prophet Muhammad died, Muslim scholars wrote down stories about what he had said and done. They also wrote down facts about who told each story. Some of the stories were retold many times before they were written down, and some stories did not agree in every detail resulting in the detailed study of hadith by scholars to compare between those hadith.

Muslim scholars collected all of these Hadith in books and compared them to each other. They decided which Hadith were most likely to be true records of the Sunnah, that is, the words and actions of Muhammad. Muslims see the Sunnah as an important source of guidance, along with the Qur'an. Islam is the complete religion so nothing could be changed about it. It gives a complete code of life.

Historically, not all Muslims believed in the hadiths. For example, Mu'tazilites rejected the hadiths as the basis for Islamic law, while at the same time accepting the Sunnah and ijma. For Mu'tazilites, the basic argument for rejecting the hadiths was that "since its essence is transmission by individuals, [it] cannot be a sure avenue of our knowledge about the Prophetic teaching unlike the Qur’an about whose transmission there is a universal unanimity among Muslims". Further, those who claim to obey the Qur'an alone while rejecting external sources such as the hadiths and the previous revelations are known as "Qur'anists".

• Quranism
• Criticism of hadith