2/23-24 — The challenge
"If you are in doubt about what We have sent down to Our servant, then bring a sūra like it; and call your witnesses besides God, if you are truthful. If you do not do it — and you never will — then guard yourselves against the fire whose fuel is people and stones."
In the second verse it was said "there is no rayb in it". Here the same word comes back: "if you are in rayb".
Set the two sentences side by side and the structure the sūra builds appears: the doubt is not in the book, the doubt is in you. And the claim is not left standing empty — a test is proposed.
Note also: for doubt the particle fī (in) is used once more. The pattern we saw in the fifth verse continues — negative states are things one is "inside".
The word used in speaking of the Prophet is "Our servant". This is a consistent choice of the Qurʾān; the same word is used when the Ascension is recounted: "He who took His servant by night…" (al-Isrāʾ 17/1).
Even where the highest stations are named, the title is "servant". Prophethood is not a rank above servanthood; it is a task within servanthood.
Arabic has two different patterns from the same root and the Qurʾān uses both: anzala and nazzala. The second (the one used here) states that the act is done piece by piece, repeatedly. That the Qurʾān came down spread over twenty-three years is recorded in the pattern of the word.
The Qurʾān makes this challenge in more than one place and on different scales: bring a discourse (al-Ṭūr 52/34), bring ten sūras (Hūd 11/13), bring one sūra (al-Baqara 2/23; Yūnus 10/38). The classical reading takes this as a gradual narrowing — the demand was made smaller and smaller and was still not met. But since the order in which these sūras came down is not known with certainty, the chronological construction "much was asked first, then it was reduced" is a supposition; that has to be stated.
Here one must be honest. This claim is a literary claim, and judgements of literary superiority are in part subjective; it is not possible to prove by any laboratory measure that a text is "without equal". The Qurʾān's own proof is historical: this challenge was made to a community who were the most accomplished users of the language and who had every reason to refuse, and that community chose to meet the text not with imitation but with weapons.
This proof deserves to be taken seriously, but it does not close the matter on its own. In my judgement the most defensible side of the claim is not beauty of style but wholeness: that a text spread over twenty-three years, over continually changing conditions, over war and peace, victory and loss, should keep its language, its measure and its inner consistency. I write this not as a ruling but as my own assessment.
وَلَن تَفْعَلُوا۟ — "you never will". In Arabic lan is a definite negation directed at the future. For a text to issue such a ruling about itself means leaving itself permanently open to a test.