are His words: “Whoever kills a soul—without it being in retaliation for another soul or for spreading corruption in the land—it is as though he has killed all mankind; and whoever saves a life, it is as though he has saved all mankind” (5:32).
In this verse Allah explains that whoever kills a person not in retribution for a life taken, nor because of corruption committed in the land, is reckoned as one who has killed all humanity. The reason is that the sanctity of the Muslims is indivisible: whoever violates the sanctity of one Muslim has, in effect, violated the sanctity of every Muslim. The case is parallel to denying any single messenger; that, too, counts as denying all the messengers. For this reason the Almighty says: “The people of Noah denied the messengers” (26:105), even though they had denied only one, for no messenger had been sent before Noah and those sent after him were not met by his people. Thus, whoever rejects a single messenger is as though he had rejected them all, and whoever unlawfully kills a single soul is as though he had killed all people, because the Muslims share one collective inviolability. Conversely, whoever gives life to a soul—that is, strives to revive it and rescue it from destruction—is as though he had given life to all humankind.
Saving a life and rescuing it from ruin sometimes pertains to a calamity over which a person has no control and is purely from Allah’s decree—for example, a fire breaks out in a man’s house and you attempt to save him; this counts as bringing a soul to life. At other times it concerns something within human reach: a man intends to assault another and kill him, and you intervene, standing between them and shielding him from death. In that moment you have brought a soul to life, and whoever does so is as though he had given life to all people, for reviving a single Muslim is equivalent to reviving humanity.
The words of the Exalted, “without [rightful retaliation for] a life,” indicate that one who kills in retribution for a life already taken is excused and bears no sin. Allah the Exalted says: “We prescribed for them therein that a life for a life…”