وَيَنْقَلِبُ إِلَى أَهْلِهِ مَسْرُورًا ۞ إِنَّهُ كَانَ فِي أَهْلِهِ مَسْرُورًا
The fortunate person will return to family joyfully; the other had lived joyfully among family. (84:9, 13)
“Masrūran” occurs twice, but the value and consequence of the joy differ by context. The first is happiness following an easy reckoning; the second describes a carefree earthly life that ignored return and accountability. Shared wording does not entail identical rhetorical meaning.
The emphatic “innahu kāna” begins explaining the other person's character and conduct. Reading the two occurrences of “masrūran” as interchangeable would ignore discourse context. This is a refined contrast embedded within repetition.