Hebrews 10:27

but only a terrifying prospect of judgment and that fiery indignation which is going to devour God's enemies.

Hebrews 10:31

It is a terrifying thing to fall into the hands of the ever living God!

Revelation 6:15-17

The kings of the earth, the great men, the military leaders, the rich, the mighty -- everybody, whether slaves or free hid themselves in the caves and among the rocks of the mountains.

Treasury of Scripture Knowledge

Summary

That they feared greatly, because Gibeon was a great city, as one of the royal cities, and because it was greater than Ai, and all the men thereof were mighty.

Bible References

They feared

Hebrews 10:27
but only a terrifying prospect of judgment and that fiery indignation which is going to devour God's enemies.
Revelation 6:15
The kings of the earth, the great men, the military leaders, the rich, the mighty -- everybody, whether slaves or free hid themselves in the caves and among the rocks of the mountains.