For it shall be - It shall happen in the time of the calamity that shall come upon Moab.

As a wandering bird - (See Isaiah 10:14.) 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 would Moab be when the inhabitants were driven from their dwellings. The reason why 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 shall 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 shall be driven from their homes, and shall wander about, and endeavor to flee from the invasion which has come upon the land. By the apprehension, therefore, 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 endeavor 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 vale 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 here referred to; and, indeed, permanent bridges among the ancients were things almost unknown. Hence, they selected the places where the streams were most shallow and gentle, as the usual places of crossing.

For it shall be,.... Or, "otherwise it shall be" (z); if ye do not pay this tribute:

that as a wandering bird cast out of the nest: or, "as a wandering bird, the nest sent out": that is, as a bird that has forsaken its nest, and wanders about, and its young ones are turned out of the nest, scarcely fledged, and unable to shift for themselves, but flutter about here and there, trembling and frightened, see Proverbs 26:2,

so the daughters of Moab shall be at the fords of Arnon: turned out of their houses, wandering up and down, not knowing where to go; unable to help themselves, and in the utmost fright and consternation, fleeing to the very borders of their land, as the fords of Arnon were, see Numbers 21:13.

(z) "alioqui", Junius & Tremellius, Piscator.

The advice does not remain without effect, but they embrace it eagerly."And the daughters of Moab will be like birds fluttering about, a scared nest, at the fords of the Arnon." "The daughters of Moab," like "the daughters of Judah," for example, in Psalm 48:12, are the inhabitants of the cities and villages of the land of Moab. They were already like birds soaring about (Proverbs 27:8), because of their flight from their own land; but here, as we may see from the expression תהיינה ... והיה, the simile is intended to depict the condition into which they would be thrown by the prophet's advice. The figure (cf., Isaiah 10:14) as well as the expression (cf., Isaiah 17:2) is thoroughly Isaiah's. It is a state of anxious and timid indecision, resembling the fluttering to and fro of birds, that have been driven away from their nest, and wheel anxiously round and round, without daring to return to their old home. In this way the daughters of Moab, coming out of their hiding-places, whether nearer or more remote, show themselves at the fords of the Arnon, that is to say, on the very soil of their old home, which was situated between the Arnon and Wady el-Ahsa, and which was now devastated by the hand of a foe. לארנון מעברות we should regard as in apposition to benoth Moab (the daughters of Moab), if ma‛bâroth signifies the coast-lands (like ‛ebrē in Isaiah 7:20), and not, as it invariably does, the fords. It is locative in its meaning, and is so accentuated.

For it shall be, that, as a {b} wandering bird cast out of the nest, so the daughters of Moab shall be at the fords of Arnon.

(b) There is no remedy but that you must flee.

16:2 Cast out - Which knows not whither to go. Arnon - Which was the border of the land of Moab, where they were, with design to flee out of their land, tho' they knew not whither.

cast...: or, a nest forsaken

2. cast out of . nest-rather, "as a brood cast out" (in apposition with "a wandering bird," or rather, wandering birds), namely, a brood just fledged and expelled from the nest in which they were hatched [Horsley]. Compare Isa 10:14; De 32:11.

daughters of Moab-that is, the inhabitants of Moab. So 2Ki 19:21; Ps 48:11; Jer 46:11; La 4:22 [Maurer].

at the fords-trying to cross the boundary river of Moab, in order to escape out of the land. Ewald and Maurer make "fords" a poetical expression for "the dwellers on Arnon," answering to the parallel clause of the same sense, "daughters of Moab."

16:1-5 God tells sinners what they may do to prevent ruin; so he does to Moab. Let them send the tribute they formerly engaged to pay to Judah. Take it as good advice. Break off thy sins by righteousness, it may lengthen thy quiet. And this may be applied to the great gospel duty of submission to Christ. Send him the lamb, the best you have, yourselves a living sacrifice. When you come to God, the great Ruler, come in the name of the Lamb, the Lamb of God. Those who will not submit to Christ, shall be as a bird that wanders from her nest, which shall be snatched up by the next bird of prey. Those who will not yield to the fear of God, shall be made to yield to the fear of every thing else. He advises them to be kind to the seed of Israel. Those that expect to find favour when in trouble themselves, must show favour to those in trouble. What is here said concerning the throne of Hezekiah, also belongs, in a much higher sense, to the kingdom of Jesus Christ. Though by subjection to Him we may not enjoy worldly riches or honours, but may be exposed to poverty and contempt, we shall have peace of conscience and eternal life.