Sahih Bukhari Volume 009, Book 083, Hadith Number 040.
Narrated By Ash-Sha'bi : I heard Abu Juhaifa saying, "I asked 'Ali, 'Have you got any Divine literature apart from the Qur'an?' (Once he said... apart from what the people have?) 'Ali replied, 'By Him Who made the grain split (germinate) and created the soul, we have nothing except what is in the Qur'an and the ability (gift) of understanding Allah's Book which He may endow a man with and we have what is written in this paper.' I asked, 'What is written in this paper?' He replied, 'Al-'Aql (the regulation of Diya), about the ransom of captives, and the Judgment that a Muslim should not be killed in Qisas (equality in punishment) for killing a disbeliever.'" (See Hadith No. 283,Vol. 4)