Tafsir of Al-Anbiya' 21:49

"Those who fear their Lord..."

His saying, the Almighty: "Those who fear their Lord" is in the genitive case in terms of grammatical position, serving as a laudatory description for the righteous (al-muttaqin), or as an appositive (badal), or an explanatory clause (bayan). It may also be in the accusative or nominative case, serving as an expression of praise. The intended meaning, assuming an ellipsis, is "those who fear the punishment of their Lord."

His saying, the Glorified: "unseen" (bi-al-ghayb), is a circumstantial qualifier (hal) related to the object—meaning they fear that while it is absent from them and not witnessed by them. In this, there is an allusion to the disbelievers, as they are not affected by warning unless they witness what they have been warned about.

Al-Zajjaj said: It is a circumstantial qualifier related to the subject—meaning they fear Him while absent from the eyes of people. Ibn Atiyyah favored this view. It has also been said: They fear Him with their hearts.

"And they are of the Hour apprehensive"

That is, fearful, by way of emphasizing their concern. The sentence may be taken as a conjunction linked to the relative clause (al-silah), or as a new independent sentence (istinaf). The prepositional phrase was placed forward to observe the rhythm of the verse endings. The specific mention of their apprehension regarding the Hour, after describing them with general fear, is to signal that it is the greatest of all created things, and to explicitly state that their state is the opposite of those who demand [the punishment] hastily. The preference for the nominal sentence structure serves to indicate that their state concerning the Hereafter is one of perpetual apprehension.