Sahih al-Bukhari 111

Narrated Ash-Shu`bi:

Abu Juhaifa said, “I asked `Ali, ‘Have you got any book (which has been revealed to the Prophet (ﷺ) apart
from the Qur’an)?’ `Ali replied, ‘No, except Allah’s Book or the power of understanding which has
been bestowed (by Allah) upon a Muslim or what is (written) in this sheet of paper (with me).’ Abu
Juhaifa said, “I asked, ‘What is (written) in this sheet of paper?’ `Ali replied, it deals with The Diyya
(compensation (blood money) paid by the killer to the relatives of the victim), the ransom for the
releasing of the captives from the hands of the enemies, and the law that no Muslim should be killed
in Qisas (equality in punishment) for the killing of (a disbeliever).