A summary of it: "If you were truthful, you would have disputed it and produced a sura, but you didn't [coundn't] and you won't [be able to]. One concludes from this that you weren't truthful, while your enemy, the Messenger (Upon whom be peace), is truthful and that the Qur'an is miraculous. So this obliges you to believe in him so that you may fear [avoid] the punishment [of the Fire]!" See how miraculous is this conciseness of the Revelation!

Then, saying: "if you cannot (in lam taf'alu)" instead of 'but you haven't [done it]' (lâkin mâ taf'alûn), it indicates through the doubt denoted by "if' conformity with their suspicions (zann), and through its denoting a condition that is the opposite of the following sentence, necessitates the opposite of the previous one. Then, in place of the result, that is, the opposite of the previous one, I mean "but you weren't truthful," it mentions the third of three successive consequences (lâzim) of the cause ('ilia), which is "then fear the Fire (fa-'ttaqû al-nâr)," to frighten, intimidate, and threaten them.

As for "if you cannot (lit. have not) (in lam taf'alû):" its signifying the past by virtue of the "lam - not" and the future through the "if (in)" is in order to direct attention towards their past, as though it is saying to them: "Look at your decorated orations and gilded Seven Hanging Odes: are any of them equal to [the Qur'an] or close to it even, or in the same class?"

The choice of "do, make (taf'alû)" rather than 'bring' (ta'tû) suggests two points:

The First: It infers that the source of the [Qur'an's] miraculousness and inimitability (i'jâz) is their impotence ('ajz), and the source of their impotence is [related to] action (fi'l) not to the work (athar). [That is, the source of their impotence is their inability to 'do' or produce something similar to the Qur'an, not the work itself].

The Second: It is for conciseness. For just as in grammar [the verbal root] fa 'ala is used to depict the patterns and forms of the verb, so in the literary styles it is used as the summary of actions and stories, as though it were a pronoun expressing whole sentences and alluding to them.

"And of a surety you cannot (wa lan taf'alû):" the future and emphasis expressed by "Ian" infer definiteness, and this indicates that the speaker is confident and serious and that he has no doubts concerning what he is saying. And this is a sign that there is no trickery or deception [in what he says and does].

The use of "then fear (fa-'ttaqû)" instead of 'avoid' (tajannabû), [both express the same meaning, but al-ittiqâ' follows on after belief, while avoidance does not have this secondary meaning] implies as a substitute for the consequence [of the above conditional sentence] the sentence: "Believe and avoid associating partners with Allâh (shirk), which is a cause of entering Hell-fire."