Exodus 19:15 KJV
And he said unto the people, Be ready against the third day: come not at your wives.
Exodus 19:15, King James Version
In context
14 And Moses went down from the mount unto the people, and sanctified the people; and they washed their clothes.
15 And he said unto the people, Be ready against the third day: come not at your wives.
16 And it came to pass on the third day in the morning, that there were thunders and lightnings, and a thick cloud upon the mount, and the voice of the trumpet exceeding loud; so that all the people that was in the camp trembled.