Exodus 19:16-18

16On the morning of the athird day there were bthunders and lightnings and ca thick cloud on the mountain and a very loud dtrumpet blast, so that all the people in the camp etrembled. 17Then fMoses brought the people out of the camp to meet God, and they took their stand at the foot of the mountain. 18Now gMount Sinai was wrapped in smoke because the Lord had descended on it in fire. The smoke of it went up like the smoke of a kiln, and hthe whole mountain trembled greatly.

Deuteronomy 4:11

11And iyou came near and stood at the foot of the mountain, while jthe mountain burned with fire to the heart of heaven, wrapped in darkness, cloud, and gloom.
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