Abu Juhaifah said: I asked Sayyiduna Ali, may Allah be pleased with him: O Commander of the Faithful! Do you have any revelation (from Allah) besides the Book of Allah? (Meaning, anything that is not present in the Holy Qur’an?) He replied: No, by Him Who split the grain and created the soul, I know nothing except the Qur’an, except for the understanding (and insight) which Allah grants to whomever He wills from His Book, and what is written on this scroll. I asked: What is written on this scroll? He said: The rulings of blood money (diyah), the release of captives, and the issue that a Muslim is not killed in retaliation for a disbeliever.
From the question of Abu Juhaifah and the answer of Sayyiduna Ali radi Allahu anhu, there is a refutation of the Shia who say that the Qur’an is not complete, that some surahs are missing from it, and that the complete Qur’an was with Sayyiduna Ali radi Allahu anhu after the Messenger of Allah sallallahu alayhi wa sallam, then it was passed on to each Imam, until it reached Imam Mahdi, who is in occultation, and when he appears, the complete Qur’an will be spread in the world. Ma’adh Allah (Allah forbid), all these are lies and superstitions. Sayyiduna Ali radi Allahu anhu said: “By the One Who split the grain and created the soul, we have only that knowledge which others have (nor is there any special bequest with us)......”
In light of this hadith, the scholars have reached consensus (ijma‘) that a Muslim should not be killed in retaliation for a harbi disbeliever, nor for a dhimmi disbeliever.
This is the position of the majority of scholars and the Ahl al-Hadith. According to Imam Abu Hanifah rahimahullah, a Muslim will be killed in retaliation for a dhimmi disbeliever.
This hadith is against their view, and their evidence is not strong. Imam Malik rahimahullah said: If a Muslim kills a dhimmi disbeliever, then he will be killed in retaliation for him.
Imam Shafi‘i rahimahullah said: A Muslim should not be killed in any case; this is the correct view. The ahadith of Sayyiduna Ali and Sayyiduna Umar radi Allahu anhuma support this opinion.