Surat Hud (107-108)

{خَالِدِينَ فِيهَا مَا دَامَتِ السَّمَاوَاتُ وَالأَرْضُ إِلاَّ مَا شَاء رَبُّكَ إِنَّ رَبَّكَ فَعَّالٌ لِّمَا يُرِيدُ} (هود : 107 )

107- They shall stay in Hell forever as long as the heavens and the earth exist.

This is an Arabic expression to describe the continuity of something, so Allah addressed them with something they know.

Some people said that the meaning is the heavens and the earths of the Hereafter. The exception comes according to the will of Allah who does what He wills in regard to the wretched and the happy ones. And the meaning is: Allah shall bring out disobedient Muslims from Hell by the intercession of intercessors then the mercy of Allah comes to bring out those who never did a good deed but they once said: No god but Allah. No one shall stay in Hell except those who are destined to stay there forever; this is the view of many scholars, anciently and recently.

{وَأَمَّا الَّذِينَ سُعِدُواْ فَفِي الْجَنَّةِ خَالِدِينَ فِيهَا مَا دَامَتِ السَّمَاوَاتُ وَالأَرْضُ إِلاَّ مَا شَاء رَبُّكَ عَطَاء غَيْرَ مَجْذُوذٍ} (هود : 108 )

108- As for the happy ones from the faithful and the followers of the Messengers, their final destination shall be Paradise as long as the heavens and the earth exist except if Allah wills other wisely.

The meaning of exception is: They do not deserve the bliss by something they had done but they enter Paradise by the will of Allah according to the view of Ibn Kathir.

There is no doubt about the perpetuity of the dwellers of Heavens, therefore Allah consoled their hearts by this saying: "A gift without an end." i.e., an everlasting blessing for the people of Paradise.