Du'a for exam

اللَّهُمَّ لَا سَهْلَ إِلَّا مَا جَعَلْتَهُ سَهْلًا، وَأَنْتَ تَجْعَلُ الْحَزْنَ إِذَا شِئْتَ سَهْلًا

Allahumma la sahla illa ma ja'altahu sahlan, wa anta taj'alul-hazna idha shi'ta sahlan.

O Allah, there is nothing easy except what You make easy, and You make the difficult easy if it be Your Will.

Ṣaḥīḥ Ibn Ḥibbān 974