“ ‘O my Lord! Show me (Yourself), that I may look upon You’” Allaah said to him: “ ‘You cannot see Me, but look upon the mountain; if it stands still in its place then you shall see Me.’ So when his Lord appeared to the mountain, He made it collapse to dust.” So the mountain crumbled before Moosa as he was looking on, and “Moosa (Moses) fell down unconscious” So he lost consciousness, because he was watching something that he could not bear. “Then when he recovered his senses he said: ‘Glory be to You, I turn to You in repentance and I am the first of the believers.’” [Quotations from al-A’raaf 7:143 – interpretation of the meaning]. So he repented to Allaah for having asked this question, because it was asking for something that was not possible, and Allaah says (interpretation of the meaning): 

“Invoke your Lord with humility and in secret. He likes not the aggressors”

[al-A’raaf 7:55]