indicates [the Qur’an’s] silencing them [by answering] the source of their doubts, namely, “Why wasn’t it revealed to him all at once?” That is, [the Qur’an told them:] “You produce some and let’s see it, even if only a single short piece!”
The choice of the word “sūra” signifies too that there are numerous benefits in the Qur’an being divided into suras, as has been elucidated by al-Zamakhsharī, and that this unusual method contains many subtle points.
The phrase “like thereunto (min mithlihi)” signifies two [possible] things: that is, [the suffixed pronoun “hi” refers] either to the thing revealed (al-munzal) [the Qur’an – that is, “produce a sura like one of the Qur‘an’s”], or to the one to whom it was revealed (al-munzal ‘alayhi) [the Messenger – that is, “get someone unlettered like him to produce it”]. If it is the former, it should be phrased “mithli sūratin minhu,” but it is expressed as “min mithlihi,” indicating that the second possibility is taken into account. That is, “You can invalidate his case with your disputing only if someone unlettered like him [the Messenger] does it.” It indicates too that [the Qur’an’s] miraculousness could be invalidated only if disputed by a collection [a literary work, majmū‘a – that is, if the sura produced was part of a complete work] like [the Qur’an].
The phrase also allusively directs attention to the other scriptures that were revealed like the Qur’an, so that the listener may weigh them up in his mind and understand the Qur’an’s elevated nature.
The sentence “and call your witnesses [and helpers if there are any] besides Allah (wa’d‘ū shuhadā’akum min dūn Allāh):” the choice of “call (ud‘ū)” instead of ‘seek the help or assistance of’ indicates that those who might respond to them and defend them are not non-existent but are there [with them] and do not need to be called.
The word “witnesses (shuhadā’)” comprises three meanings: your authorities on the Arabic language, those who observe [witness] you, and your gods.
In respect of the first it silences them by rebutting their argument that their own inability does not prove that their literary leaders lack the power [to imitate the Qur’an].
In respect of the second it dumbfounds them by cutting short their excuse that they had no witnesses, for every outlook and way has defenders and witnesses.
In respect of the third it rebukes and derides them, asking why their gods which they look to for benefits and to repel harm, do not help them in this matter that is troubling them.