Sayyiduna Abu Juhaifah (may Allah be pleased with him) reports that I asked Sayyiduna Ali (may Allah be pleased with him): Do you have anything (such as a command or statement) from the Messenger of Allah (peace and blessings be upon him) besides the Qur'an? He replied: By Him Who split the grain and created the soul! There is nothing except this scroll and the Book of Allah, and the understanding which Allah has granted. I asked: What is in this scroll? He said: (The rulings of) blood money (diyah), the freeing of captives, and that a Muslim is not to be killed in retaliation for a disbeliever.
Hadith Referenceالمنتقى ابن الجارود / كتاب الطلاق / 794