Exodus 19:18 in the King James Version
And mount Sinai was altogether on a smoke, because the LORD descended upon it in fire: and the smoke thereof ascended as the smoke of a furnace, and the whole mount quaked greatly.
Context
17 Moses led the people out of the camp to meet God; and they stood at the lower part of the mountain.
18 All of Mount Sinai smoked, because the LORD descended on it in fire; and its smoke ascended like the smoke of a furnace, and the whole mountain quaked greatly.
19 When the sound of the trumpet grew louder and louder, Moses spoke, and God answered him by a voice.