The Lord said to Moses, ‘I am going to come to you in a dense cloud, so that the people will hear when I speak with you and will always believe you.’ Moses reported the people’s words to the Lord,
You came down on Mount Sinai, and spoke to them from heaven. You gave them impartial ordinances, reliable instructions, and good statutes and commands.
See to it that you do not reject the one who speaks. For if they did not escape when they rejected him who warned them on earth, even less will we if we turn away from him who warns us from heaven.
Mount Sinai was completely enveloped in smoke because the Lord came down on it in fire. Its smoke went up like the smoke of a furnace, and the whole mountain shook violently.