Tafsir of Al-Hijr 15:48

(No fatigue shall touch them therein) — that is, in those Gardens — (nor shall they ever be removed from it).

Fatigue is a state of weariness, either because they will have nothing there requiring the effort of seeking what they need, as everything they desire will be attained without the performance of any work whatsoever; or because such weariness will not overtake them even if they engage in vigorous movements, due to the perfection of their strength. In some traditions, it is said that the strength of one of them is the strength of forty men of the men of this world.

The sentence is an explanatory or descriptive resumption; or it is a circumstantial qualifier for the pronoun in "(being) in Gardens," or for the pronoun in "brothers," or for the pronoun in "facing one another," or for the pronoun in "upon thrones."

(Nor shall they ever be removed from it) — meaning they are eternal therein. The intent is the continuity of the negation, for the perfection of bliss lies in eternity. This is redundant with "(being) secure" if one intends by that security from being removed from the Garden or transferred from it; this repetition is employed for the sake of emphasis and importance. If, however, it is intended to mean security from the cessation of the bliss, delight, and health they possess, then it is not redundant.

Some have scrutinized the necessity of this redundancy, arguing that being secure from a thing does not necessitate its non-occurrence, such as the security of the disbelievers from the plan of Allah, for example. It has also been suggested that the intended meaning might be the cessation of their own selves through death, not removal from the Garden. This has been countered by noting that the latter is extremely far-fetched, for it is not said of a dead person that he is "in it," even if he were buried there. As for the former, when Allah Almighty gives them glad tidings of security from it, how could the non-occurrence of that be imagined?