Therefore the abundance they have gotten, and that which they have laid up, shall they carry away to the brook of the willows.
Therefore - Because of the devastation of the land.
The abundance they have gotten - Hebrew, yitraah (H3502), 'left;' i:e., that which is over and above the necessaries of life.
Shall they carry away to the brook of the willows. The fugitives flee from Nimrim, where the waters have failed, to places better watered. Hebrew, nachal ha'arabim: margin, 'valley of the Arabians' - i:e. to the valley on the boundary between them and Arabia Petrea; now Wady-el-Arabah. Arabia means a desert.