إِلَّا الَّذِينَ آمَنُوا وَعَمِلُوا الصَّالِحَاتِ فَلَهُمْ أَجْرٌ غَيْرُ مَمْنُونٍ
Except those who believe and do righteous deeds; for them is an unfailing reward. (95:6)
Illā introduces the exception, combining belief with righteous action. The fāʾ before lahum carries the statement toward the promised consequence; the prepositional phrase may be analyzed as a fronted predicate and ajrun as its delayed nominal subject.
If the preceding 'lowest' describes eschatological ruin, the exception distinguishes the saved. If it is read as advanced age, the assurance of continued reward takes a different explanatory form. Ghayru mamnūn is commonly explained as a reward that is not cut off.