Exodus 19:9-11

Amplified Bible, Classic Edition

⁹ And the Lord said to Moses, Behold, I come to you in a thick cloud, that the people may hear when I speak with you and believe you and remain steadfast forever. Then Moses told the words of the people to the Lord.

¹⁰ And the Lord said to Moses, Go and sanctify the people [set them apart for God] today and tomorrow, and let them wash their clothes

¹¹ And be ready by the third day, for the third day the Lord will come down upon Mount Sinai [in the cloud] in the sight of all the people.