This reading is from the special Torah portion read on the Shabbat during festival of Sukkot.
And the Lord said to Moses, "I will also do this thing that you have asked; for you have truly gained My favor and I have singled you out by name." He said, "Oh, let me behold Your Presence!" And He answered, "I will make all My goodness pass before you, and I will proclaim before you the name Lord, and the grace that I grant and the compassion that I show. But," He said, "you cannot see My face, for man may not see Me and live."
And the Lord said, "See, there is a place near Me. Station yourself on the rock and, as My Presence passes by, I will put you in a cleft of the rock and shield you with My hand until I have passed by. Then I will take My hand away and you will see My back; but My face must not be seen."