Exodus 19:10, 15, 22
Exodus 19:10 KJV
And the LORD said unto Moses, Go unto the people, and sanctify them to day and to morrow, and let them wash their clothes
Exodus 19:15 KJV
And he said unto the people, Be ready against the third day: come not at your wives.
Exodus 19:22 KJV
And let the priests also, which come near to the LORD, sanctify themselves, lest the LORD break forth upon them.