Albert Barnes Commentary Isaiah 16:2

"For it shall be that, as wandering birds, as a scattered nest, so shall the daughters of Moab be at the fords of the Arnon." — Isaiah 16:2 (ASV)

For it will be – It will happen in the time of the calamity that will come upon Moab.

As a wandering bird – . The same idea is presented in Proverbs 27:8:

As a bird that wanders from her nest,
So is a man that wandereth from his place.

The idea here is that of a bird driven away from her nest, where the nest is destroyed, and the young fly about without any home or place of rest. So Moab would be when the inhabitants were driven from their dwellings.

The reason this is introduced seems to be to enforce what the prophet had said in the previous verse: the duty of paying the usual tribute to the Jews and seeking their protection. The time is coming, says the prophet, when the Moabites will be driven from their homes, and when they will need that protection which they can obtain by paying the usual tribute to the Jews.

The daughters of Moab – The females will be driven from their homes, and will wander about, and attempt to flee from the invasion that has come upon the land. Therefore, with the fear that their wives and daughters would be exposed to this danger, the prophet calls upon the Moabites to secure the protection of the king of Judah.

At the fords of Arnon – Arnon was the northern boundary of the land of Moab. They would attempt to cross that river and thus flee from the land and escape the desolations that were coming upon it. The river Arnon, now called Mujeb, flows in a deep, frightfully wild, and rocky valley of the same name (Numbers 21:15; Deuteronomy 2:24; Deuteronomy 3:9), in a narrow bed, and forms at this time the boundary between the provinces of Belka and Karrak (Seetzen).

Bridges were not common in the times referred to here; indeed, permanent bridges among the ancients were almost unknown. Hence, they selected the places where the streams were most shallow and gentle as the usual places of crossing.