Every person lives in this universe for a limited time. Death is the unquestionable end for this life. Nothing can save men from death: “Wherever you are, death will overtake you, though you are in lofty towers.” (4:78)
After Barzakh those who enter heaven will be there forever: “Those who are in awe of the Beneficent God in secret and come with a penitent heart: Enter it in peace, that is the day of abiding” (50:33,34)
Those people who enter Hell are of two kinds. Disbelievers who are against the truth will stay there forever. But those believers who will enter hell for their bad deeds will finally enter heaven after they will have been cleansed.
“So as to those who are unhappy, they shall be in the fire; for them shall be sighing and groaning in it, abiding therein so long as the heavens and the earth endure, except as your Lord please; surely your Lord is the mighty doer of what He intends. And as to those who are made happy, they shall be in the garden, abiding in it as long as the heavens and the earth endure, except as your Lord please; which shall never be cut off “(11:106-108)
“And (as to) those who disbelieve, their guardians are Shaytans who take them out of the light into the darkness; they are the inmates of the fire, in it they shall abide.” (2:257)