Tafsir of Qaf 50:37

"Indeed in that"—meaning in the destruction [of the past nations] or in what has been mentioned in the Surah—"is a reminder"—a memorial and an admonition—"for whoever has a heart"—meaning an attentive heart that perceives truths, for he who does not comprehend or understand is in the position of one who does not exist. It is stated in al-Kashf that "for whoever has a heart" is a metaphorical representation.

"Or who listens"—meaning he lends his ear to what is recited to him of revelation—"while he is present"—meaning present in the sense of being a witness, signifying presence. The intent here is one who is perceptive, for the one who is not perceptive is placed in the position of the absent. This is either a metaphor (isti'arah) or a synecdoche (majaz mursal), and the former is more appropriate.

It has been permitted that it be from "witnessing" as a description of the believer, because he bears witness to the truthfulness of what was revealed and that it is a revelation from Allah the Almighty, which motivates him to listen well. Or, it is a description of him based on the words of the Almighty: "That you may be witnesses over the people." It is as if it were said: "He is among the witnesses," i.e., the believers of this nation, making it a metonymy in both cases. Regarding the first of these two, it is also permitted that it not be a metonymy, in the sense that he is a witness through certainty, not like the witnessing of the People of the Book.

According to Qatadah, the meaning is: for whoever hears the Qur'an from the People of the Book while being a witness to its truthfulness due to what he finds in his own book of its description. However, the most appropriate to the flow of the discourse—otherwise, the fullness of the acquisition of witnessing [is lost]—is the view that "while he is present" (wa huwa shahid) is a circumstantial qualifier (hal) for the pronoun in "who listens" (alqa), not a conjunction to "listened" (alqa), as is not hidden from one who has a heart.

[The meaning is:] "Or he listens while he is present." The intent is that in what was done to the nations of the past, or in the aforementioned, there are signs providing a reminder for one of two groups: one who has a heart that stops him [from sinning] before Allah the Almighty, or one who has an attentive ear along with a present mind—meaning one who possesses a readiness to accept from the scholar if he is not a scholar himself. The "or" is used to prevent the exclusion [of either case], as it is possible for a person to be a scholar and [at the same time] ready to accept [knowledge] from a scholar. Some have stated that it serves to categorize the one who is reminded into a reciter and a listener, or into a scholar and a learner, or into a sage who is fully prepared and needs nothing other than reflection on what he already possesses, and one who is deficient and in need of learning; such a one is reminded if he approaches with both [faculties] and removes all impediments. So reflect.

Al-Sulami, Talhah, al-Suddi, and Abu al-Barhasm read 'aw ulqiya' (passive voice), with 'al-sam'u' (the hearing) in the nominative case as a deputy of the subject. The omitted subject is either the one expressed by the relative pronoun (man) or otherwise. In the second case, the meaning is "for whoever has had his hearing cast [toward the truth] by another, who opened his ear but did not present his mind." As for the individual himself, he has cast his hearing while being present and perceptive; thus, the description—meaning being a witness—is the cornerstone of the speech. It was expressed in the verse with this phrasing to emphasize his perceptiveness and presence. According to the first [reading], the meaning is "for whoever casts his hearing while he is present and perceptive," then another relative pronoun is implied after "or." Thus, the possessor of the heart and the one who casts [his hearing] are distinct. However, even if one does not imply it, it is permissible that they be two separate people, or one person viewed in two states: the state of being perceptive by himself, and the state of casting his hearing while present and attentive to one who is perceptive by himself, for "whoever" (man) encompasses every single individual.