Exodus 19:12-19
12 Put limits for the people around the mountain and tell them, ‘Be careful that you do not go up the mountain or touch the foot of it. Whoever touches the mountain shall surely be put to death.
13 He shall surely be stoned or shot with arrows; not a hand is to be laid on him. Whether man or animal, he shall not be permitted to live.’ Only when the ram’s horn sounds a long blast may they go up to the mountain.”
14 After Moses had gone down the mountain to the people, he consecrated them, and they washed their clothes.
15 Then he said to the people, “Prepare yourselves for the third day. Abstain from sexual relations.”
16 On the morning of the third day there was thunder and lightning, with a thick cloud over the mountain, and a very loud trumpet blast. Everyone in the camp trembled.
17 Then Moses led the people out of the camp to meet with God, and they stood at the foot of the mountain.
18 Mount Sinai was covered with smoke, because the Lord descended on it in fire. The smoke billowed up from it like smoke from a furnace, the whole mountain trembled violently,
19 and the sound of the trumpet grew louder and louder. Then Moses spoke and the voice of God answered him.