Hell is eternal in Islam, no doubt:
Qur'an 39:72:
“Enter the gates of Hell to abide eternally therein, and wretched is the residence of the arrogant.”
2:167
"and those that followed say, 'O if only we might return again and disown them, as they have disowned us!' Even so God shall show them their works. O bitter regrets for them! Never shall they issue from the Fire"
"As to those who reject Faith, - if they had everything on earth, and twice repeated, to give as ransom for the penalty of the Day of Judgment, it would never be accepted of them, theirs would be a grievous penalty. Their wish will be to get out of the Fire, but NEVER will they get out therefrom: their penalty will be one that endures." 5:36-37
"Taste ye then - for ye forgot the Meeting of this Day of yours, and We too will forget you - taste ye the Penalty of Eternity for your (evil) deeds!" S. 32:14
"Such is the requital of the enemies of Allah,- the Fire: therein will be for them the Eternal Home: a (fit) requital, for that they were wont to reject Our Signs." 41:28
"Enter ye therein in Peace and Security; this is a Day of Eternal Life!" 50:34
"If they accuse thee of falsehood, say: "Your Lord is full of mercy all-embracing; but from people in guilt never will His wrath be turned back." 6:147
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If these are misunderstandings or mistranslations of the Qur'an, even though Arabic scholars have for 1,400 years taught that the Qur'an says hell is eternal, then the Qur'an's a very poorly written book because it can't state this simple matter without error. It's therefore far from the 'perfect', 'divine' book it claims to be. In fact the Qur'an claims to be so miraculous that it challenges anyone to write a single sentence as good, let alone better, than it. Well here we go:
"Hell is temporary. All the dead return to their creator eternally in paradise"
There I've now defeated the Qur'an's challenge, as my statement is clear and therefore more 'miraculous'.

