Exodus 19:21

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.

When the sound of the trumpet grew louder and louder, Moses spoke, and God answered him by a voice.

The LORD came down on Mount Sinai, to the top of the mountain. The LORD called Moses to the top of the mountain, and Moses went up.

Let the priests also, who come near to the LORD, sanctify themselves, lest the LORD break out on them.”

Moses said to the LORD, “The people can’t come up to Mount Sinai, for you warned us, saying, ‘Set bounds around the mountain, and sanctify it.’”

The LORD said to him, “Go down! You shall bring Aaron up with you, but don’t let the priests and the people break through to come up to the LORD, lest he break out against them.”