Exodus 19:17 And Moses brought forth the people out of the camp to meet with God; and they stood at the nether part of the mount.
Exodus 19:18 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.
Exodus 19:19 And when the voice of the trumpet sounded long, and waxed louder and louder, Moses spake, and God answered him by a voice.
Exodus 19:20 And the LORD came down upon mount Sinai, on the top of the mount: and the LORD called Moses up to the top of the mount; and Moses went up.

What's in bold should read I am exeeding fearful.

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I remember reading it, Hebrews 12:21 quotes it, but it's no longer there in Exodus yet I went there to quote it for a brother.