The lion has roared, who will not fear? the Lord GOD has spoken, who can but prophesy?
All Commentaries on Amos 3:8 Go To Amos 3
Cyril of Alexandria
AD 444
In other words, he is saying, if by the roaring of the lion, the strongest of wild animals, a person would not be so unfeeling and insolent as not to feel the impact of terror, how could it be that when God speaks in His great might and bids them proclaim what they have been told, they would not be in fear of the bidder?