So too it is an allusion to the depths of mankind's heedlessness.

As for the "ayyu," it is used to single out [a person or a group] from the mass and infers that all the universe is being addressed, and humankind is specified since men bear the trust in the form of "fard kifâya" [that is, it is human beings that are charged with performing worship]. So if they are lax [in doing this], they transgress against the rights of all [other] beings.

Also, in "ayyu" is an eloquent subtlety in that its conciseness is followed by the descriptive "people (al-nâs)." Then the "hâ" being a substitute for the second part of the genitive construction indicates that [its purpose] is to alert those summoned with the vocative interjection "yâ - O!"

"People (al-nâs)\" being an active participle derived from [the verbal noun] nisyân, meaning forgetfulness, it indicates censure or reproof. That is, "O you people! How can you forget the pre-eternal covenant (al-mithâq al-azalî)? It indicates too an excuse; that is: "O you people! Your neglect can be due only to a mistake or forgetfulness; it can't be deliberate or serious!"

As for "worship! (u'budû)" since it is the conclusion (or apodosis) of the general summons to all the classes [of people] mentioned above, it points to obedience, and indicates sincerity, and hints at continuance, and alludes to divine unity. That is, obey! Be sincere and constant [in worship]! Increase [your worship]! Profess the divine unity!

"Your Lord and Sustainer (rabbakum)" indicates that just as worship should be desired and sought since it is an elevated relation, an illustrious connection; it should be sought too since it is [a way of] serving and offering thanks to the One who nurtures and raises you, of whom you are in need.

Now for the parts of the phrase: "who created you and those [who lived] before you (alladhî khalaqakum wa alladhîna min qablikum):"

As a relative pronoun, "who (alladhî)" is known only in so far as it is qualified by the relative clause. [For instance, all that is known about "the one who went" is that he has gone.] Thus, [here "Lord and Sustainer" being governed by "who"] it infers that knowledge of Allâh the Most High can only be in respect of His actions and works, and not His essence.¹

Then by virtue of its signifying determined, regular creation rather than the [mere] giving of existence (îjâd) or giving rise to (inshâ'), "created (khalaqa)" indicates that by nature the human being is turned toward the obligation [of worship]. It infers too that worship is a duty, for it is the result and 'wage' of creation. But [this wage is not the reward for worship;] the reward is purely a favour of Allâh the Most High.

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1.Nursi, İsârâtûl-İ'caz [Abdülmecid], 218