Surah Al-Baqarah — Ayah 55 (2:55)
وَإِذۡ قُلۡتُمۡ يَٰمُوسَىٰ لَن نُّؤۡمِنَ لَكَ حَتَّىٰ نَرَى ٱللَّهَ جَهۡرَةٗ فَأَخَذَتۡكُمُ ٱلصَّٰعِقَةُ وَأَنتُمۡ تَنظُرُونَ ٥٥
English translation (Saheeh International)
And [recall] when you said, "O Moses, we will never believe you until we see Allāh outright"; so the thunderbolt took you while you were looking on.
Brief commentary
Also, remember when you shamelessly addressed Moses (peace be upon him), saying that you would not believe him until you saw Allah with your own eyes, in the open before you, and the lightning struck you and killed you, whilst some of you looked at the others.