Exodus 19:9-11

New International Version - UK

⁹ The Lord said to Moses, ‘I am going to come to you in a dense cloud, so that the people will hear me speaking with you and will always put their trust in you.’ Then Moses told the Lord what the people had said.

¹⁰ And the Lord said to Moses, ‘Go to the people and consecrate them today and tomorrow. Make them wash their clothes ¹¹ and be ready by the third day, because on that day the Lord will come down on Mount Sinai in the sight of all the people.