Exodus 19:18-19

18Mount Sinai was covered with smoke, because the LORD descended on it in fire. The smoke billowed up from it like smoke from a furnace, and the whole mountain Most Hebrew manuscripts; a few Hebrew manuscripts and Septuagint and all the people trembled violently.

19As the sound of the trumpet grew louder and louder, Moses spoke and the voice of God answered him. Or and God answered him with thunder