Tafsir of Fussilat 41:28

"That" is a demonstrative referring to the recompense previously mentioned, and it is the subject (mubtada'). His saying, Exalted is He: "the recompense of the enemies of Allah" is its predicate (khabar); meaning, that which was mentioned of the recompense is a recompense prepared for His enemies, Exalted is He. His saying, Glorified is He: "the Fire" is an explanatory appositive ('atf bayan) for "recompense," or a substitute (badal), or the predicate of an omitted subject.

It is also permissible that "that" is the predicate of an omitted subject—meaning, the matter is that—and "recompense" is the subject, and "the Fire" is its predicate. In this case, the demonstrative refers to the content of the preceding sentence. His saying, Exalted is He: "for them therein is the home of eternity" is an independent sentence confirming what preceded it.

It is also permissible that "the Fire" is the subject and this sentence is its predicate, meaning it is the very place of their residence, provided that "in" (fi) is for abstraction (tajrid), as it is said regarding His saying, Exalted is He: "There has certainly been for you in the Messenger of Allah an excellent pattern," and the saying of the poet: "And in Allah, if they do not grant justice, is a just decree." This is the extraction from a matter possessing a quality of another like it, as a hyperbole for that quality.

It is also permissible to say that the intent is to mention the quality, and the "home" was only mentioned as a preamble, as if it were said: "for them therein is eternity." It is also said that the speech is taken at its literal meaning and the locative sense is real, the intent being that they have in the Fire—which contains the [various] levels—a specific home in which they will abide eternally; and the first is more eloquent.

"A recompense for what they used to deny of Our verses."

This is in the accusative case due to an implied verb—meaning, "they are recompensed with a recompense"—or due to the preceding verbal noun (masdar), for a verbal noun can govern an object like its verb, as in His saying, Exalted is He: "For indeed, Hell is your recompense, a sufficient recompense." The first "bi" (bama - for what) is connected to "recompense," and the second is connected to "they deny," having been placed before it for the purpose of relative exclusivity, alongside the consideration of the rhyme endings; meaning: because of what they used to deny of Our true verses, not the matters that ought to be denied.

Some considered "denial" to be a metaphor for the vain talk (laghw) resulting from it; meaning: a recompense for what they used to engage in vain talk regarding Our verses.