The parallel between Quran 5:32 and Mishnah Sanhedrin 4:5 is real and worth taking seriously. But a parallel with an earlier Jewish tradition does not by itself prove human borrowing, especially when the Quran openly presents the ruling as something decreed for the Children of Israel.
The strongest form of the criticism
The critic's case is not silly. Mishnah Sanhedrin 4:5 is earlier than Islam and contains a famous teaching: destroying one life is like destroying a whole world, and saving one life is like saving a whole world. Quran 5:32 says something very close. The verse even begins by saying this was decreed for the Children of Israel, which seems to place it inside Jewish moral tradition.
So the argument is: Prophet Muhammad (PBUH) must have heard Jewish teachings circulating in Arabia, adapted one of them, and presented it as revelation. If that is right, critics say, the Quran is not independently revealed but dependent on rabbinic material.
What the verse actually says
Because of that, We decreed upon the Children of Israel that whoever kills a soul unless for a soul or for corruption in the land - it is as if he had killed all mankind; and whoever saves one - it is as if he had saved all mankind. And Our messengers had certainly come to them with clear proofs. Then indeed many of them, after that, throughout the land, were transgressors.
Quran 5:32
The Quran is not hiding the Israelite setting. It states it. The verse comes after the story of the two sons of Adam, where the first murder shows how one killing can open the door to a whole pattern of human violence. Classical commentators generally read the verse as a divine ruling and moral lesson given to the Children of Israel, then recited to the Muslim community as guidance.
The Mishnah's wording is indeed similar, but its setting is different: it appears in a discussion of court procedure and the seriousness of capital testimony. The Quran places the teaching in a prophetic and moral history: murder, divine law, messengers, and later human transgression. It also adds legal limits - "unless for a soul or for corruption in the land" - which are not a casual decorative phrase but part of the verse's legal meaning.
Why similarity is not enough
The Quran repeatedly describes itself as confirming earlier revelation while also judging and correcting what people inherited:
And We have revealed to you the Book in truth, confirming what came before it of the Scripture and as a criterion over it.
Quran 5:48
So, from the Quran's own viewpoint, overlap with earlier communities is expected. If a truth was given to earlier prophets, traces of it may survive in Jewish teaching, Christian teaching, or oral tradition. The presence of a shared teaching is not an embarrassment to revelation; it is exactly the sort of thing the Quran says will happen.
Nor does the historical evidence force one conclusion. A historian may say, "This resembles a known Jewish tradition, and such traditions may have circulated orally." That is fair. But "therefore the Prophet (PBUH) copied it and falsely claimed revelation" is not a historical fact; it is an interpretation built on a prior assumption that revelation cannot occur.
What this proves, and what it does not
It proves that Quran 5:32 has a strong conceptual and verbal resemblance to a teaching known in rabbinic Judaism. It also proves that the Quran itself connects this teaching with the Children of Israel.
It does not prove plagiarism. It does not prove access to a Mishnah manuscript. It does not prove that the Quran is merely derivative. And it does not undermine the Islamic claim unless one first assumes that God could not reveal a truth previously preserved, partly or fully, among an earlier religious community.
A sober reading is simple: the parallel is real, but it fits the Quran's own claim to confirm earlier divine guidance. The objection raises a good historical observation; it does not carry the theological conclusion critics often attach to it.