Albert Barnes Commentary Isaiah 56:9

"All ye beasts of the field, come to devour, [yea], all ye beasts in the forest." — Isaiah 56:9 (ASV)

All you beasts of the field - This evidently begins a new subject and refers to an invasion of the land of Judea.

In the previous chapter, the prophet had comforted the people with the assurance of the Messiah's coming and with the fact that they would be enlarged by the accession of the Gentiles. He proceeds here to a more disagreeable part of the subject.

The design is to reprove particularly the sins of the rulers of the people and to assure them that such conduct would incur the vengeance of heaven. The sins reproved are indolence and inattention to duty (Isaiah 56:10–12); a spirit of self-indulgence and of slumber, avarice and selfishness, and luxury and intemperance.

Lowth supposes the vengeance referred to here to be the invasion of the land by the Chaldeans, and perhaps by the Romans.

Grotius supposes that it refers to the Egyptians, and to bands of robbers from the Chaldeans, Syrians, Moabites, and Ammonites. Vitringa, strangely enough, refers it to the barbarous nations that broke in upon the Christian church to lay it waste and destroy it during the decline of the Roman Empire, particularly the Huns, Saracens, Turks, Turcomans, Tartars, etc.

But the connection seems to demand that it should be understood of some events not far distant from the time of the prophet, which would be a proper punishment of the crimes then existing.

According to this interpretation, I suppose the reference here is to the invasion of the land by the Chaldeans. They would come as wild beasts to spread terror and devastation before them.

And so great were the national crimes that the prophet calls on them to come and devour all before them. The comparison of invaders to wild beasts is not uncommon in the Scriptures. Thus (Jeremiah 12:9):

My heritage is to me as a speckled bird,
The birds round about are against her;
Come, you, assemble all the beasts of the field,
Come to devour.

So (Jeremiah 50:17):

Israel is a scattered sheep;
The lions have driven him away;
First the king of Assyria has devoured him,
And last this Nebuchadrezzar, king of Babylon, has broken his bones.

See also (Isaiah 9:11).