It is narrated from Qays bin Ubad (may Allah be pleased with him): Al-Ashtar (al-Nakha'i) and I went to Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) on the day of the Battle of the Camel, and I asked: Did the Messenger of Allah (peace and blessings be upon him) entrust you with any special instruction, apart from the people in general? He said: No, except for this writing. And he took out a scroll from the sheath of his sword, in which was written: "The blood of all the believers is equal (in retaliation); even the lowest of them may grant protection (to someone) and it is binding on behalf of all; they are as one hand (united) against their enemies; no believer shall be killed in retaliation for a disbeliever, nor shall one under a covenant (a dhimmi) be killed while his covenant stands." This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it.