—and every other impostor who laid claim to prophethood. If even a single statement of such a person is open to doubt—indeed, if it is merely possible that he fabricated it deliberately or uttered it in error—then it is impermissible to credit him with anything else he attributes to Allah. One may only rely on what he relates from Allah if he is a truthful messenger who never lies, whether intentionally or inadvertently; for everyone whom Allah sends must, of necessity, be truthful in everything he transmits from Allah, never lying therein—deliberately or by mistake.

[The Messenger’s Truthfulness and His Immunity from Falsehood]

This is a point on which all people agree—Muslims, Jews, Christians, and others alike: they concur that a messenger must be truthful and protected from error in what he conveys from Allah, never attributing to Allah any falsehood, whether by accident or on purpose. Without that, the very purpose of the message could not be fulfilled.

As Moses, peace be upon him, said to Pharaoh:

“O Pharaoh, I am indeed a messenger from the Lord of the worlds; it is incumbent upon me that I say nothing about Allah except the truth.” ⦗Al-Aʿrāf 104-105⦘

In the well-known reading, he is stating that he is worthy, deserving, constant, and firmly resolved never to speak of Allah except the truth; while according to the other reading he declares that it is obligatory upon him not to say anything about Allah but the truth.