Exodus 19:7-11

So Moses went down and called the elders of the people together. He told them all the words the LORD had commanded him to say. All the people answered together, “We will do everything he has said.” Then Moses took their answer back to the LORD. And the LORD said to Moses, “I will come to you in a thick cloud and speak to you. The people will hear me speaking with you and will always trust you.” Then Moses told the LORD what the people had said. The LORD said to Moses, “Go to the people and have them spend today and tomorrow preparing themselves. They must wash their clothes and be ready by the day after tomorrow. On that day I, the LORD, will come down on Mount Sinai, and all the people will see me.