And Moses went down from the mount unto the people
 The same day that he went up, the fourth day of the month: 
 and sanctified the people;
 instructed them and ordered them what they should do for their sanctification, in order to their hearing the law from the mouth of the Lord: 
 and they washed their clothes;
 as the Lord had directed Moses to enjoin them, and as he had commanded them, (See Gill on Exodus 19:10).