This reading is from the special Torah portion read on the Shabbat during festival of Sukkot. The complete reading for the intermediate Shabbat is Exodus 33:12-34:26.
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."