(11) باب أَيُقَادُ الْمُسْلِمُ بِالْكَافِرِ
Narrated Qays ibn Abbad :
I and Ashtar went to Ali and said to him: Did the Messenger of Allah (ﷺ) give you any instruction about anything for which he did not give any instruction to the people in general? He said: No, except what is contained in this document of mine. Musaddad said: He then took out a document. Ahmad said: A document from the sheath of his sword. It contained: The lives of all Muslims are equal; they are one hand against others; the lowliest of them can guarantee their protection. Beware, a Muslim must not be killed for an infidel, nor must one who has been given a covenant be killed while his covenant holds. If anyone introduces an innovation, he will be responsible for it. If anyone introduces an innovation or gives shelter to a man who introduces an innovation (in religion), he is cursed by Allah, by His angels, and by all the people. Musaddad said: Ibn AbuUrubah's version has: He took out a document.
Reference: Sunan Abi Dawud 4530
In-book reference: Book 41, Hadith 37
English translation: Book 40, Hadith 4515