The restriction expressed by "that it is the truth (annahû al-haqq)" [that is, that being right is restricted to that parable], is a sign that contrary to what they claim, it is [only] this [parable of the gnat] that is approved [by the science of rhetoric] and not found disagreeable. [Accordingly, another metaphor would not be acceptable even if free of defect], for freedom from defect does not prove the perfection [of a thing].

The phrase "from their Sustainer (min rabbihim)" indicates that their aim and purpose is to deny [that the parable] is revealed [by their Sustainer],

The [conjunction] "as for (ammâ)" in "whereas (lit. as for) those who reject faith (lit. disbelieve) (wa ammâ alladhîna kafarû)" signifies emphasis, corroboration, and particularization.

The substitution of "those who reject faith (lit. disbelieve)" for 'the disbelievers,' although the latter is more concise, infers that their denial arises from disbelief and leads to it, as has been mentioned.

And "[they] say (fa-yaqûlûna)" is used rather than 'but they do not know,' although as has been mentioned the latter is clearer, because to make allusion is more succinct; that is: the person who disbelieves does not know the truth and this causes him to waver, and this leads [firstly] to denial and then to asking disparaging questions.

Moreover, "[they] say" infers that just as they are themselves misguided, so with their words they lead others astray.

Now [the positioning and relationships of) the parts of the phrases "By it He causes many to go astray, and many He guides aright (yudillu bihi kathîran wa yahdî bi-hi kathîran):"

Consider this: here, the arrangement (al-tartîb) requires that the second [phrase] comes first [to correspond to the precedence of "those who believe" previously in the verse], but since the aim is to refute the [disbelievers'] vacillating, questioning, repugnant objections that smack of denial, "He causes to go astray" is of greater importance.

The non-use of the verbal nouns 'guidance' and 'misguidance' and use of the imperfect tense of the verbs indicates that the darkness of their disbelief intensifies proportionately to the gradual revelation [of the Qur'an], just as the believers' faith increases proportionately in luminosity.

Moreover, as the reply [to their question: "What means Allâh by this parable?], the verbal form suggests it is elucidating the situations of the two groups, and explaining [the choice of] the reasons [for them].