Deuteronomy 4:11-15

11You came forward and stood at the foot of the mountain, 1and the mountain was burning with fire to the heart of the heavens: darkness, cloud, and thick gloom. 12Then the Lord spoke to you from the midst of the fire; you heard the sound of words, but you saw no form--there was only a voice. 13So He declared to you His covenant which He commanded you to perform, that is, 2the Ten 3Commandments; and 4He wrote them on two tablets of stone. 14The Lord commanded me at that time to teach you statutes and judgments, so that you would perform them in the land where you are going over to take possession of it.

15“So 5be very careful 6yourselves, since you did not see any 7form on the day the Lord spoke to you at Horeb from the midst of the fire,