The Quran Verse
Surah 10:37–38:
And this Qur'an is not such as could ever be produced by other than Allah... Or do they say, 'He has forged it?' Say, 'Then bring a surah like unto it and call upon whomever you can besides Allah...'
This is the Tahaddi (Challenge) of the Quran. Critics argue this is a subjective and logically circular argument.
There are no objective criteria for what makes a Surah "like" another. If the criteria are poetic style, linguistic beauty, or moral impact, many contemporary poets (and later authors) produced works that their audiences found equally or more compelling.
Using the uniqueness of a book as proof of its divine origin is a non-sequitur; every unique literary work is, by definition, "un-reproducible" in its exact form.