Albert Barnes Commentary Jeremiah 48:19

"O inhabitant of Aroer, stand by the way, and watch: ask him that fleeth, and her that escapeth; say, What hath been done?" — Jeremiah 48:19 (ASV)

Aroer - On the Arnon, due south of Dibon. If Dibon falls, the turn of Aroer will come next, and therefore its inhabitants are to be on the lookout, asking for news.