Quran promises of Reward to believers, and punishment to disbelievers.
Precision in description
The arabic words mentioned in Quran about entering Paradise or Hellfire are:
Khalid (adjective): to remain/stay for a long period of time.
Abad (adverb): Eternally, without an end.
Now if you study the way those two words were used to describe the stay in Paradise or Hellfire please consider the following two examples:
But those who believe and do righteous deeds - We will admit
them to gardens beneath which rivers flow, wherein they abide forever.
For them therein are purified spouses, and We will admit them to
while in the same Sura(chapter) [4-13]
These are the limits [set by] Allah, and whoever obeys Allah and His
Messenger will be admitted by Him to gardens [in Paradise] under which
rivers flow, abiding eternally therein; and that is the great
A beautiful observation, of the number of times the word eternally forever mentioned reveals mercy of the Al-mighty
when related to Paradise 8 times.
when related to hellfire 3 times.
And Allah knows best.