Al-An'am 6:15

قُلْ إِنِّىٓ أَخَافُ إِنْ عَصَيْتُ رَبِّى عَذَابَ يَوْمٍ عَظِيمٍ

Qul innī akhāfu in ʿaṣaytu rabbī ʿadhāba yawmin ʿaẓīmin

Say, "Indeed I fear, if I should disobey my Lord, the punishment of a tremendous Day."