Qur'an 7:143

وَلَمَّا جَآءَ مُوسَىٰ لِمِيقَـٰتِنَا وَكَلَّمَهُۥ رَبُّهُۥ قَالَ رَبِّ أَرِنِىٓ أَنظُرْ إِلَيْكَ ۚ قَالَ لَن تَرَىٰنِى وَلَـٰكِنِ ٱنظُرْ إِلَى ٱلْجَبَلِ فَإِنِ ٱسْتَقَرَّ مَكَانَهُۥ فَسَوْفَ تَرَىٰنِى ۚ فَلَمَّا تَجَلَّىٰ رَبُّهُۥ لِلْجَبَلِ جَعَلَهُۥ دَكًّا وَخَرَّ مُوسَىٰ صَعِقًا ۚ فَلَمَّآ أَفَاقَ قَالَ سُبْحَـٰنَكَ تُبْتُ إِلَيْكَ وَأَنَا۠ أَوَّلُ ٱلْمُؤْمِنِينَ

And when Moses came to Our appointed tryst and his Lord had spoken unto him, he said: My Lord! Show me (Thy Self), that I may gaze upon Thee. He said: Thou wilt not see Me, but gaze upon the mountain! If it stand still in its place, then thou wilt see Me. And when his Lord revealed (His) glory to the mountain He sent it crashing down. And Moses fell down senseless. And when he woke he said: Glory unto Thee! I turn unto Thee repentant, and I am the first of (true) believers.