Exodus 19:9-11

Living Bible

⁹ Then he said to Moses, “I am going to come to you in the form of a dark cloud, so that the people themselves can hear me when I talk with you, and then they will always believe you. ¹⁰ Go down now and see that the people are ready for my visit. Sanctify them today and tomorrow, and have them wash their clothes. ¹¹ Then, the day after tomorrow, I will come down upon Mount Sinai as all the people watch.