مَا وَدَّعَكَ رَبُّكَ وَمَا قَلَىٰ ۝ وَلَلْآخِرَةُ خَيْرٌ لَّكَ مِنَ الْأُولَىٰ ۝ وَلَسَوْفَ يُعْطِيكَ رَبُّكَ فَتَرْضَىٰ

The system of this world has been so formulated that here the day dawns and night also falls. Only with the occurrence of both is the system perfect. Similarly, for the proper development of a man, it is necessary that he should have hardship as well as easy circumstances. In this world, hardship befalls the servant of God in order to activate his latent capabilities. Impediments are put in his way so that he may strive to make his future brighter than his present.

— Source: Tazkirul Quran (Maulana Wahiduddin Khan) via Quran.com (93:3)