English Standard Version
Indeed, so terrifying was the sight that Moses said, “I tremble with fear.”

American Standard Version
and so fearful was the appearance, that Moses said, I exceedingly fear and quake:

Berean Study Bible
The sight was so terrifying that even Moses said, “I am trembling with fear.”

Douay-Rheims Bible
And so terrible was that which was seen, Moses said: I am frighted, and tremble.

English Revised Version
and so fearful was the appearance, that Moses said, I exceedingly fear and quake:

King James Bible
And so terrible was the sight, that Moses said, I exceedingly fear and quake:)

World English Bible
and so fearful was the appearance, that Moses said, "I am terrified and trembling."

Young's Literal Translation
and, (so terrible was the sight,) Moses said, 'I am fearful exceedingly, and trembling.'

Hebrews 12:21 Additional Translations ...