Deuteronomy 4:12 in the King James Version
And the LORD spake unto you out of the midst of the fire: ye heard the voice of the words, but saw no similitude; only ye heard a voice.
Context
11 You came near and stood under the mountain. The mountain burned with fire to the heart of the sky, with darkness, cloud, and thick darkness.
12 The LORD spoke to you out of the middle of the fire: you heard the voice of words, but you saw no form; you only heard a voice.
13 He declared to you his covenant, which he commanded you to perform, even the ten commandments. He wrote them on two stone tablets.