They that fled stood under the shadow (z) of Heshbon because of the force: but (a) a fire shall come out of Heshbon, and a flame from the midst of Sihon, and shall devour the corner of Moab, and the crown of the head of the tumultuous ones.
(z) They fled there thinking to have comfort from the Amorites.
(a) The Amorites had destroyed the Moabites in times past, and now because of their power the Moabites will seek them for help.