Deuteronomy 4
11 Ref You came near and stood under the mountain; and the mountain burned with fire to the heart of the sky, with darkness, cloud, and thick darkness.
12 Ref Yahweh spoke to you out of the midst of the fire: you heard the voice of words, but you saw no form; only [you heard] a voice.
13 Ref He declared to you his covenant, which he commanded you to perform, even the ten commandments; and he wrote them on two tables of stone.
14 Ref Yahweh commanded me at that time to teach you statutes and ordinances, that you might do them in the land where you go over to possess it.
15 Ref Take therefore good heed to yourselves; for you saw no manner of form on the day that Yahweh spoke to you in Horeb out of the midst of the fire.