Du'a for success in an exam or interview: O Allah, I ask You for the goodness of this day

اللَّهُمَّ إِنِّي أَسْأَلُكَ خَيْرَ هَذَا الْيَوْمِ فَتْحَهُ وَنَصْرَهُ وَنُورَهُ وَبَرَكَتَهُ وَهُدَاهُ

Allahumma inni as'aluka khayra hadhal-yawmi fathahu wa nasrahu wa nurahu wa barakatahu wa hudah

O Allah, I ask You for the goodness of this day, its victory, its help, its light, its blessings, and its guidance.

Sunan Abī Dāwūd 5084