Tafsir of Al-Furqan 25:65

And those who say: "Our Lord! Avert from us the torment of Hell. Verily, its torment is ever an inseparable punishment.'' meaning, ever-present and never ending. Al-Hasan said concerning the Ayah,

إن عذابها كان غراما

(Verily, its torment is ever an inseparable, permanent punishment), Everything that strikes the son of Adam, then disappears, does not constitute an inseparable, permanent punishment. The inseparable, permanent punishment is that which lasts as long as heaven and earth. This was also the view of Sulayman At-Taymi

إنها ساءت مستقرا ومقاما