﴿ وَإِذْ قُلْتُمْ يَٰمُوسَىٰ لَن نُّؤْمِنَ لَكَ حَتَّىٰ نَرَى ٱللَّهَ جَهْرَةًۭ فَأَخَذَتْكُمُ ٱلصَّٰعِقَةُ وَأَنتُمْ تَنظُرُونَ ﴾

“And [remember] when you said, "O Moses. indeed we shall not believe thee unto we see God face to face!" - whereupon the thunderbolt of punishment overtook you before your very eyes.”

Please check ayah 2:56 for complete tafsir.