Tafsir of Az-Zukhruf 43:74

"Indeed, the criminals..." i.e., those who are deeply rooted in crime and perfected in it, and they are the disbelievers. It is as if it were said: Indeed, the disbelievers "are in the punishment of Hell, abiding eternally."

The intent of this is supported by making them the counterpart to those who believe in the verses, in His saying, the Exalted: "Those who believed in Our verses." Thus, the verse does not provide evidence for the eternal stay of disobedient believers in Hell, as the Mu'tazila and the Khawarij have gone. It does not cause harm that there is no explicit mention regarding the ruling of [disobedient believers], based on the view that those intended by "those who believed" are the righteous, due to His saying, the Exalted: "O My servants, no fear will there be concerning you this Day, nor will you grieve." As for the claim that "those who believed" includes them [the disobedient] because the effective cause is their faith and submission—that which is within it is not hidden [to the discerning].

The adverbial phrase [in the punishment of Hell] is connected to "abiding eternally," and "abiding eternally" is the predicate of "Indeed." It is also permitted that the adverbial phrase itself be the predicate, and "abiding eternally" be its active participle, due to its reliance [on the preceding noun].