Exodus 19:14–17

14 Then Moses came down from the mountain to the people and consecrated them, and they washed their clothes. 15 He said to the people, “Be prepared by the third day. Do not have sexual relations with women.”

16 On the third day, when morning came, there was thunder and lightning, a thick cloud on the mountain, and a very loud blast from a trumpet, so that all the people in the camp shuddered. 17 Then Moses brought the people out of the camp to meet God, and they stood at the foot of the mountain.