Passage
And so terrible was that which was seen, Moses said: I am frighted, and tremble.
And so terrible was that which was seen, Moses said: I am frighted, and tremble.
Hebrews 12:19 And the sound of a trumpet and the voice of words, which they that had excused themselves, that the word might not be spoken to them.
Hebrews 12:20 For they did not endure that which was said: and if so much as a beast shall touch the mount, it shall be stoned.
Hebrews 12:21 And so terrible was that which was seen, Moses said: I am frighted, and tremble.
Hebrews 12:22 But you are come to mount Sion and to the city of the living God, the heavenly Jerusalem, and to the company of many thousands of angels,
Hebrews 12:23 And to the church of the firstborn who are written in the heavens, and to God the judge of all, and to the spirits of the just made perfect,
The verse centers on "terrible", "seen", "moses", "said", "frighted", and "tremble". It is saying that the verse draws attention to "terrible" and "seen", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 20's "For they did not endure that which..." into verse 22's "But you are come to mount Sion...", so "terrible" and "seen" belong inside that flow. In Hebrews context, the local focus is Christ, faith, and discipleship.
A plain takeaway is to answer the verse's own emphasis on "terrible" and "seen" with trust shaped by these words, not by a vague optimism outside the passage.