Surah Al-An'aam, Verse 15
قُلْ إِنِّىٓ أَخَافُ إِنْ عَصَيْتُ رَبِّى عَذَابَ يَوْمٍ عَظِيمٍۢ
Translation — Sahih International
Say, "Indeed I fear, if I should disobey my Lord, the punishment of a tremendous Day."
Source
Kur'an-ı Kerim, En'âm Suresi 6:15
https://kuran.diyanet.gov.tr/mushaf/kuran-meal-2/6-suresi-15-ayet