The LORD said to Moses, “Behold, I will come to you in a dense cloud, so that the people will hear when I speak with you, and they will always put their trust in you.” And Moses relayed to the LORD what the people had said.
Jewish Publication Society of America Version (JPS1917) - Exodus 19:9 >And the LORD said unto Moses: 'Lo, I come unto thee in a thick cloud, that the people may hear when I speak with thee, and may also believe thee for ever.' And Moses told the words of the people unto the LORD.