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On the fact that it is impossible to have faith in any prophet whatsoever while denying the prophethood of Muhammad, the Messenger of Allah—may Allah bless him and grant him peace—and that whoever rejects his prophethood is even more inclined to reject the prophethood of every other messenger.

This becomes clear from several perspectives:

One of them: The earlier prophets proclaimed his forthcoming prophethood and commanded their nations to believe in him. Hence, whoever denies his prophethood has belied the prophets before him in what they related and contradicted them in what they enjoined—namely, faith in him. Affirming him is an inescapable corollary of affirming them, and when the corollary (1) is negated, the principle that entails it is, beyond doubt, negated as well.

The proof of this inseparability lies in the many arguments previously discussed which, taken together, render certain that he—peace and blessings be upon him—was mentioned in the divine scriptures on the tongues of the prophets. Once this linkage is established, the absence of the consequent necessarily entails the absence of its antecedent.

The second perspective: The call of Muhammad ibn ʿAbd Allāh—may Allah’s blessings and peace be upon him—is the very call of all the messengers before him, from the first to the last. Whoever rejects his message therefore rejects the message of all his brother-messengers, for every one of them came with what he came with. Thus, by denying him the denier is claiming that what he brought is false, and this amounts to denying every messenger Allah ever sent and every scripture Allah revealed (2). It is impossible for someone to deem his message true while simultaneously accusing him of lying against Allah. This is self-evidently clear.