Exodus 19:16 So it came about on the third day, when it was morning, that there were thunder and lightning flashes and a thick cloud upon the mountain and a very loud trumpet sound, so that all the people who were in the camp trembled.

Exodus 19:21 Then the LORD spoke to Moses, "Go down, warn the people, so that they do not break through to the LORD to gaze, and many of them perish.

Exodus 20:18 All the people perceived the thunder and the lightning flashes and the sound of the trumpet and the mountain smoking; and when the people saw it, they trembled and stood at a distance.

Galatians 3:19 Why the Law then? It was added because of transgressions, having been ordained through angels by the agency of a mediator, until the seed would come to whom the promise had been made.

Hebrews 12:18 For you have not come to a mountain that can be touched and to a blazing fire, and to darkness and gloom and whirlwind, (NASB ©1995)