Surah Al-An'am, Verse 15

قُلۡ إِنِّيٓ أَخَافُ إِنۡ عَصَيۡتُ رَبِّي عَذَابَ يَوۡمٍ عَظِيمٖ١٥

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."