Tafsir of An-Nazi'at 79:9

"Their eyes humbled," meaning the eyes of their people are debased out of fear. Therefore, the eyes were attributed to them; the attribution is for the slightest connection. It is permitted that "eyes" here refers to the insights (basā'ir), meaning the insights have become humbled, perceiving nothing. Their humiliation is used as a metonymy for their lack of perception, for the glory of insight lies only in perception. It was debated whether hearts are non-perceptive on the Day of Resurrection, and it was answered that the intent is the intensity of stupor and bewilderment.

The sentence consisting of the subject and predicate is in a state of nominative case, serving as the predicate for "hearts." This has been critiqued by the argument that it is well-known that the nature of an adjective (sifah) is to be known as attributed to the described (mawsūf) by the listener, to the extent that more than one scholar has said: "Adjectives before they are known are predicates, and predicates after they are known are adjectives." Since the establishment of the trembling (wajīf) and the establishment of the humility (khushū‘) of the eyes of the owners of the hearts are equal in terms of knowledge and ignorance, treating the first as the title of the subject—as a given, established fact—and treating the second as a predicate—intended for conveying information—is purely arbitrary. Furthermore, the trembling, which is the disturbance and anxiety of the heart from the intensity of fear and dread, is more severe than the humbling of the sight, and making the more severe of two evils a mere supplementary detail while the lesser is the foundation is something unprecedented in speech. Moreover, restricting the humility to hearts described with a specific attribute, without implying generality and encompassing inclusion, diminishes the gravity of the event in a context of terrifying imagery.

You should know that what is "well-known" and what "more than one scholar has said" is not unanimously agreed upon as a universal rule, and some of the objections raised against it can be deflected based on what some eminent scholars understand regarding the permissibility of making a singular noun a predicate, and the following sentence an adjective, although this is remote. As for what was said regarding the first [view]—that making the tanwīn (in "qulūbun") one of classification while it is being worn (by the adjective) contradicts the outward meaning, and that it being like an adjective in meaning is forced and lacks fairness—this is a matter of contention. Ibn 'Atiyyah claimed that the indefinite noun was specified by His saying, "On that day," but this was critiqued on the grounds that [indefinite] bodies are not specified by temporal adverbs.

'Isām al-Dīn estimated the answer to the oath to be "Indeed, it shall surely come," and we estimate it likewise, making "On the day the trembling shakes" the subject for it in the nominative position, and making "the subsequent one follows it" an adjective for the "trembling one" (al-rājifah), treating it as indefinite because the definiteness is for a mental concept (al-'ahd al-dhihnī), like the expression, "A base person passes by me and insults me." There is much to be said about this.

It was said that the answer [to the oath] is "the subsequent one follows it," and "day" is in the accusative case governed by it, with the oath particle omitted—meaning: "By a day such as that, the subsequent one follows it." The emphatic nun was not added because there is a separation between the implied particle and the verb, though this is not very strong. Muhammad ibn 'Ali al-Tirmidhi said that the answer to the oath is, "Indeed, in that is a lesson for whoever fears," which is as you see. Similar to it is what was said that it is, "Has the story of Moses reached you?" because it is in the estimation of "It has surely reached you." Abu Hatim suggested there is an inversion and delay (taqdīm wa ta'khīr), as if it were said, "And then behold, they are in the open plain, and those who pull," but Ibn al-Anbari declared him mistaken because a sentence cannot begin with the particle "fa" (so/then). In sum, the soundest perspective is what we have presented.