Deuteronomy 4:12-15

CLV(i) 12 and Yahweh spoke to you from the midst of the fire; you were hearing the sound of words, yet you were not seeing a physical representation, nothing except a voice. 13 He told you His covenant which He instructed you to keep, the ten words. Then He wrote them on two tablets of stone. 14 And Yahweh instructed me at that time to teach you statutes and judgments, for you to obey them in the land where you are crossing over to tenant it. 15 You must be very much on guard against your soulish desires (since you saw no physical representation at all on the day Yahweh spoke to you at Horeb from the midst of the fire)