Charles Ellicott Commentary Jeremiah 49:5-6

"Behold, I will bring a fear upon thee, saith the Lord, Jehovah of hosts, from all that are round about thee; and ye shall be driven out every man right forth, and there shall be none to gather together the fugitives. But afterward I will bring back the captivity of the children of Ammon, saith Jehovah." — Jeremiah 49:5-6 (ASV)

I will bring a fear upon thee ... — As in the case of Moab, there is the doom of exile for Ammon also, but the sentence of punishment is tempered with mercy, and there is to be a return from the seemingly hopeless captivity.