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

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

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

Darby Bible Translation
and, so fearful was the sight, Moses said, I am exceedingly afraid and full of trembling;)

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:

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

Hebrews 12:21 Bible Hub
Hebrews 12:21 Bible Apps
Hebrews 12:21 Open Bible