Esodo 20:18

And all the people saw the thunderings, and the lightnings, and the noise of the trumpet, and the mountain smoking: and when the people saw it, they removed, and stood afar off. And all the people saw the thunderings, etc. - They had witnessed all these awful things before, (see Esodo 19:16), but here they seem to have been repeated; probably at the end of each command, there was a peal of thunder, a blast of the trumpet, and a gleam of lightning, to impress their hearts the more deeply with a due sense of the Divine Majesty, of the holiness of the law which was now delivered, and of the fearful consequences of disobedience.

This had the desired effect; the people were impressed with a deep religious fear and a terror of God's judgments; acknowledged themselves perfectly satisfied with the discoveries God had made of himself; and requested that Moses might be constituted the mediator between God and them, as they were not able to bear these tremendous discoveries of the Divine Majesty. "Speak thou with us, and we will hear; but let not God speak with us, lest we die;" Esodo 20:19. This teaches us the absolute necessity of that great Mediator between God and man, Christ Jesus, as no man can come unto the Father but by him.