﴿ خَٰلِدِينَ فِيهَآ أَبَدًا ۚ إِنَّ ٱللَّهَ عِندَهُۥٓ أَجْرٌ عَظِيمٌۭ ﴾

“therein to abide beyond the count of time. Verily, with God is a mighty reward!”

therein they shall abide forever khālidīna is an implied circumstance. Surely with God is a tremendous reward.