Deuteronomy 4:11
You approached and stood at the foot of the mountain, a mountain ablaze to the sky above it and yet dark with a thick cloud.
Deuteronomy 5:23
Then, when you heard the voice from the midst of the darkness while the mountain was ablaze, all your tribal leaders and elders approached me.
Exodus 19:16-18
On the third day in the morning there was thunder and lightning and a dense cloud on the mountain, and the sound of a very loud horn; all the people who were in the camp trembled.
Exodus 20:18-19
All the people were seeing the thundering and the lightning, and heard the sound of the horn, and saw the mountain smoking -- and when the people saw it they trembled with fear and kept their distance.
Hebrews 12:18-19
For you have not come to something that can be touched, to a burning fire and darkness and gloom and a whirlwind