Hadith of the Quran and Sunnah
Quran and Sunnah is a saying attributed to Muhammad (a hadith), namely I have left among you two matters by holding fast to which, you shall never be misguided: the Book of God and my Sunna. It is an often quoted saying regarding the sources of Islam. The authenticity of this hadith is rejected by many Shi'a. The concept itself is not rejected, as most Muslims hold that Islam is derived from two sources: one being infallible and containing compressed information — the Qur'an — and another being a detailed explanation of the everyday application of the principles established in the Qur'an: The Sunnah, or the living example of the Islamic prophet Muhammad.
Basis of hadith
Hadith literature refers to the oral tradition about the words and deeds (Sunnah) of the Islamic Prophet Muhammad. The statement that Islam has these two sources has been attributed to Muhammad. The Sunni Muslims accept this attribution as sahih (authentic) and hence a hadith; whereas the Shi'a Muslims reject this as being mawdoo (fabricated), and not a separate hadith, arguing that nowhere is it recorded in the Six Authentic Books of the Sunni's (Sahih Sitta). The hadith in the Six Authentic Books are generally accept as authentic throughout Islam.
The Qur'an and Sunnah hadith is reported in other books as having been said during Muhammad's Farewell Sermon atop Mount Arafat after his Last Pilgrimage.(e.g. Malik Muwatta)
Slightly varied versions are cited in many Sunni hadith works. Among those are:
- al-Jami' li-Akhlaq al-Rawi by Al-Khatib 
- Sunan al-Daraqutni 
- Sira al-Nabawiyyah by Ibn Hisham 
John Esposito explains the importance of the Hadith in Islam: "the Prophet Muhammad is seen as the living Quran, the embodiment of God's will in his behavior and words. Sunni Muslims ... take their name from the sunnah, meaning those who follow the example of the Prophet. Prof. Fatih Okumus refers to the Prophet Muhammad as "the walking Qur’an," with the Sunnah giving an example to follow.
As the sayings and deeds of Muhammad were reported via many different sources, there was disagreement about what constituted sunnah, and how that affected what should be shariah. In the ninth century Al-Shafi‘i took the view that the Quran superseded sunnah, but that sunnah could not supersede the text of the Quran. In this he rejected the version of the above hadith that said the Quran and sunnah were equal sources of guidance. (See Shafi'i school of jurisprudence.) Others, notably Ibn Kathir in his book Al-Bidaya wa'l-Nihaya, took the reverse position that sunnah as later revelation should take precedence over the Quran.
Sunni and Shi'a agreement and differences
Both Sunnis and Shi'as accept the authenticity of the related Hadith of the two weighty things (Hadith al-Thaqalayn). In this hadith, Muhammad referred to the Qur'an and Ahl al-Bayt ('people of the house', Muhammed's family) as the two weighty things. Although the hadith is accepted by both Sunnis and Shi'as, the two groups differ on the exact wording of what Muhammad said, as well how to interpret these words. The Shi'as use the Hadith of the two weighty things to prove their claim that Muhammad meant for all his successors to be from his own family (Ahl al-Bayt). The Sunnis reject this view and believe in a different interpretation of this related hadith.
The Sunnis and the Shi'as also disagree about what constitutes the "Sunnah".
Thee Sunnis generally accept this hadith, but narrowly define sunnah as the sayings and deeds of Muhammad. Although some include the "implied approvals" of Muhannad. This hadith is considered sahih by the Sunni, as stated by following scholars:
Shi'as reject this hadith and deem it to be a fabrication designed to distract from what they deem to be the real saying of Muhammad: the 'Hadith of the two weighty/precious things' (Hadith al-Thaqalayn). Since the Hadith about Quran and Sunnah was said by the Prophet in front of the larger gathering during his Farewell Sermon, and the Hadith about Quran and Ahl al-Bayt was said by the Prophet in front of the smaller gathering at Ghadir Khumm, the Shi'as believe that only the 'Hadith of the two weighty things' is authentic.
At the same time, Shi'as do agree with the meaning of the Hadith, even if they deem it a fabrication. The Shi'as believe in following the Sunnah of Muhammad, but they say that this is only possible via the Ahl al-Bayt (Muhammad's family).
The Shi'as believe that Muhammad said Hadith al-Thaqalayn multiple times in multiple settings in multiple wordings. They argue that Muhammad said Hadith al-Thaqalayn at Mount Arafat during his Farewell Sermon, at Ghadir Khumm, in the mosque of Medinah, during his last illness, and at many other places and times. The Shi'as believe that Muhammad said this hadith so many times because he wanted to stress how important it was that the Muslims only take his own descendants as leaders.
The Shi'as believe that this hadith is mutawattir, meaning that it has been related so many times by so many people that there is no doubt about its authenticity. The Shi'a claim that this hadith is the most authentic of hadiths, claiming that it has been narrated by over 35 companions of Muhammad.
The Hadith al-Thaqalayn is used by the Shi'a, among other reasons, to justify their claim of Ali's succession to Muhammad. Shi'as view this hadith as a clear indication that Muhammad wished to keep the matter of leadership within his own family, starting with his cousin Ali. They believe that Muhammad was clearly indicating that only the Ahl al-Bayt have a right to authority and leadership. It is based on this claim that the Shi'as reject the first three Sunni Caliphs, most especially as legitimate spiritual leaders of the ummah', referring to them and those who put them into power as usurpers.
Because the Shi'a believe that Muhammad said Hadith al-Thaqalayn on many occasions, the Shi'a have many different versions of what Muhammad said. One such version corresponds closely to what the Sunnis also believe in:
Muhammad said: "One of them (i.e. the Thaqalayn) is the Book of God and the other one is my select progeny ('Itratî ), that is family (Ahlul-Bayt). Beware of how you behave (with) them when I am gone from amongst you, for God, the Merciful, has informed me that these two (i.e., Quran and Ahlul-Bayt) shall never separate from each other until they reach me at the paradisial pool (hawd) (of al-Kawthar). I remind you, in the name of God, about my Ahlul-Bayt. I remind you, in the name of God, about my Ahlul-Bayt. Once more! I remind you, in the name of God, about my Ahlul-Bayt." 
The Shi'as, however, also believe in other versions of the Hadith such as:
"I have left with you something, which if you strictly adhere to, you shall never go astray–The Book of God and my progeny."
"I leave you two weighty things, if you stick to both you will never go astray after me: the Book of God and my progeny."
"I am leaving for you two precious and weighty Symbols that if you adhere to both of them, you shall not go astray after me. They are, the Book of God, and my progeny, that is, my Ahl al-Bayt. The Merciful has informed me that these two shall not separate from each other till they come to me by the Pool (of Paradise)."
It is these latter versions that more strongly support the Shi'a interpretation that Muhammad intended to keep the leadership of the Muslims within his own family and the idea of Ali as the rightful successor of Muhammad.
- Abd-Allah, Umar F. (2013). Mālik and Medina: Islamic Legal Reasoning in the Formative Period. Brill. p. 95.
- I have left among you two matters by holding fast to which, you shall never be misguided: Allah's Book and the Sunnah of His Prophet.Kabbani, Muhammad Hisham (2003). The Approach of Armageddon?: An Islamic Perspective : a Chronicle of Scientific Breakthroughs and World Events that Occur During the Last Days, as Foretold by Prophet Muhammad. Washington, D.C.: Islamic Supreme Council of America. p. 67. ISBN 978-1-930409-20-0.
- Dogan, Recep (2012). Islamic Law with the Quran and Sunnah Evidences (from a Hanafi perspective). FB Publishing. ISBN 978-0-9857512-4-1.
- "Sunnah and Hadith". quoting M. M. Azami's Studies in Hadith Methodology and Literature
- John L. Esposito, ed. (2003). "The Oxford Dictionary of Islam: Hadith". Oxford University Press.
- Vol 1 p111, 1983 ed.
- Vol 4 p.245 #149
- vol6 p.8-10
- John Esposito (2010). The Future of Islam. Oxford University Press. p. 43. ISBN 978-0-19-516521-0.
- Okumus, Fatih. "The Prophet As Example". Studies in Inter religious Dialogue 18 (2008): 82–95. Religion Index. Ebsco. Thomas Tredway Library, Rock Island, IL.
- Ahmad, Abu Umar Faruq (2010). Theory and Practice of Modern Islamic Finance: The Case Analysis from Australia. Boca Raton, Florida: BrownWalker Press. p. 59. ISBN 978-1-59942-517-7.
- Kamali, Mohammad Hashim (1999). "Law and society : the interplay of revelation and reason in the Shariah". In Esposito, John L. The Oxford History of Islam. New York: Oxford University Press. pp. 107–154, page 118. ISBN 978-0-19-510799-9.
- Ali, Syed Mohammed (2004). The Position of Women in Islam: A Progressive View. Albany, New York: State University of New York Press. p. 7. ISBN 978-0-7914-6095-5.
- full name Abu Al-Fida, 'Imad Ad-Din, Isma'il bin 'Umar bin Kathir, Al-Qurashi, Al-Busrawi
- Ali 2004, pp. 7–8
- As stated in his book Mustadrak al-Hakim, vol 1 p 93
- As stated in his work Tamhid, vol 24 p 331
- As stated in his work al-Ihkam vol 6 p 243
- Subḥānī, Jaʻfar (2001). The Doctrines of Shi'ism: A Compendium of Imami Beliefs and Practices. London: I.B. Tauris. p. 103. ISBN 978-1-86064-780-2.
- A’alam al-Wara, pp 132-133
- Musa, Aisha Y. Hadith as Scripture: Discussions on the Authority of Prophetic Traditions in Islam, New York: Palgrave, 2008.