وَأَمَّا ٱلَّذِينَ سُعِدُوا۟ فَفِى ٱلْجَنَّةِ خَـٰلِدِينَ فِيهَا مَا دَامَتِ ٱلسَّمَـٰوَٰتُ وَٱلْأَرْضُ إِلَّا مَا شَآءَ رَبُّكَ ۖ عَطَآءً غَيْرَ مَجْذُوذٍ Qur’an Hud (11:108)Waamma allatheena suAAidoo fafee aljannati khalideena feeha ma damati alssamawatu waalardu illa ma shaa rabbuka AAataan ghayra majthoothin
I.e., unless God wills to bestow on them a yet greater reward (Razi; also Manar XII, 161); or - which to my mind is more probable - unless He opens up to man a new, yet higher stage of evolution.
Except the time they spend on earth and in the grave, or except the time the sinful believers spend in Hell before being transferred to Paradise.
Exactly the same arguments apply as in the last note.
The felicity will be uninterrupted, unlike any joy or happiness which we can imagine in this life and which is subject to chances and changes, as our daily experience shows.