Exodus 19:10

19:10 The Lord said to Moses, “Go to the people and sanctify them today and tomorrow, and make them wash their clothes

Exodus 19:14-15

19:14 Then Moses went down from the mountain to the people and sanctified the people, and they washed their clothes. 19:15 He said to the people, “Be ready for the third day. Do not go near your wives.”