That a people should hear the voice of God speaking out of the midst of fire, as thou hast heard, and lived:

“"You have never seen his face." Yet Isaiah, Jeremiah, Ezekiel and many others say that they have seen him. What is it, therefore, that Christ meant here? He was introducing them to a philosophical teaching, showing gradually that with regard to God there is neither voice nor outward appearance; he is superior to such forms and sounds. Just as by saying, "You have never heard his voice," he did not mean that God utters sound but is not heard, so by saying, "You have never seen his face," he did not mean that God has outward form but cannot be seen. Neither sound nor form exists with regard to God. Indeed, in order that they might not say, "You are making a display of knowledge in vain, since God spoke only to Moses" (they actually did say, "We know that God spoke to Moses; but as for this man, we do not know where he is from"), he spoke in this way to show that with regard to God there is neither voice nor outward appearance.”

“Did ever people hear the voice of God speaking out of the midst of fire,.... None ever heard the voice of God as they did, much less speaking such words as they heard, and still less out of the midst of fire, which was their case, Deu 4:12. as thou hast heard, and live? which was stranger still, when they might have expected they should, and doubtless feared they would be, as it was wonderful they were not, consumed by it.”