Sefer HaBahir 46

1[Mar Rachumai continued,] "One text says, 'He bent the heavens and descended, a thick cloud below His feet' (2 Samuel 22:10), another text says, 'He came down upon Mount Sinai to the top of the mountain' (Exodus 19:20), and another text says, 'For from the heavens I spoke with you' (Exodus 20:19). How is this to be understood? His great fire was on the land, which was one voice, and the remainder of the voices were in the heavens, as is written 'From the heavens, you could hear His voice to instruct you; on the earth, you could see the great fire, and you heard His words from within the fire' (Deuteronomy 4:36). What is this great [fire]? And from where was the speech coming out? From within the fire, as it is said 'and you heard His words from within the fire' ?"