Commentaries:
Jamieson, Fausset, and Brown
they—the Philistine allies of Egypt who trusted in it for help against Assyria. A warning to the party among the Jews, who, though Judah was then the subordinate ally of Assyria, were looking to Egypt as a preferable ally (Isaiah 30:7). Ethiopia was their "expectation"; for Palestine had not yet obtained, but hoped for alliance with it. Egypt was their "glory," that is, boast (Isaiah 13:19); for the alliance with it was completed.
Other Jamieson, Fausset, and Brown entries containing Isaiah 20:5:
Isaiah 10:7
Isaiah 20:1
Isaiah 43:26
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