Tafsir of Qaf 50:34

(Enter it): Interpreted as if it is said to them: "Enter it." The place is intended for the performative utterance, and the plural form is used considering the meaning of "those" (alladhina).

As for His saying—Exalted be He—(in the Unseen): It relates to a deleted element, serving as a circumstantial qualifier (hal) for the subject of "feared" (khashiya), or for its object, or as an attribute to its verbal noun. That is: a fear characterized by being in the Unseen, as one fears His punishment—Glory be to Him—while He is absent from one's perception; or because He is absent from eyes, such that no one sees Him. It is said: The "bi" (in/with) refers to the instrument, and the "Unseen" refers to the heart, because it is veiled. This means: he who fears the Most Merciful (al-Rahman) with his heart, not merely with his limbs in a way that manifests fear while the heart lacks it; but this is not a significant interpretation.

The mention of the title "The Most Merciful" (al-Rahman) is to signify that, despite their fear of His punishment—Almighty be He—they are hopeful for His mercy—Glorified be He—or that their knowledge of the vastness of His mercy—Blessed and Exalted be He—does not deter them from fearing Him—Majestic is His rank. The Imam said: It is permissible that the term "The Most Merciful" points to the requirement of fear, for the meaning of "al-Rahman" is the Bestower of existence through creation, and "al-Rahim" is the Bestower of subsistence through provision. He—Glory be to Him—is al-Rahman in this world, as He brought us into existence, and al-Rahim, as He sustains our existence with provision. Therefore, the One from whom existence comes ought to be the One who is feared. The former interpretation is more worthy.

The "bi" (in/with) in His saying—Exalted be He—(with a heart) is for accompaniment (musahabah). It is also permitted that it be for transitiveness (ta’diyah), meaning: "he brought a penitent heart." The heart is described as penitent—even though this is a quality of its possessor—because the significance lies in its turning back to God—Exalted be He. The Imam has stated an unusual view, permitting the "bi" to be for causation (sababiyyah). It is as if it were said: "He did not come except because of the effects of knowledge in his heart that there is no recourse except to God—Exalted be He—so he came by means of his penitent heart." This is as you see it.

His saying—Exalted be He—(in peace) relates to a deleted element, acting as a circumstantial qualifier for the subject of "Enter it." The "bi" is for association (mulabasah), and "peace" (salam) is derived either from "safety" (salamah) or "salutation" (taslim). That is: Enter it while being associated with safety from punishment and the loss of blessings, or with salutation and greeting from God—Exalted be He—and His angels.

(That): A reference to the extended time in which some of the aforementioned matters occurred, (the Day of Eternity): Existence that has no end ever; or it is a reference to the time of entry, by implying a genitive construct—that is: "That is the day of the commencement and realization of eternity," or "the day of the decree of eternity." Or, it is a reference to the time of peace, also by implying a genitive construct—that is: "That is the day of the announcement of eternity," meaning the notification of it.