Verse 1
Isaiah 20:1. In the year that Tartan came to Ashdod — Namely, to besiege it. Tartan is mentioned (2 Kings 18:17) as one of the generals of Sennacherib, who is generally supposed to be here meant by Sargon, which was probably one of the seven names by which Jerome, on this place, says he was called. Ashdod, or Azotus, was an eminent and strong city, formerly belonging to the Philistines, in the utmost part of the land of Canaan toward Egypt. Afterward, according to Herodotus, it held out twenty-nine years against Psammitichus, king of Egypt. It is likely that at this time it belonged to Hezekiah’s dominions, and that its inhabitants expected to be relieved during the siege by the Egyptians and Cushites, or Ethiopians. The taking of it, Bishop Lowth thinks, must have happened before Sennacherib’s attempt on Jerusalem; when he boasted of his late conquests, Isaiah 37:25 : and the warning of the prophet had a principal respect to the Jews also, who were too much inclined to depend on the assistance of Egypt.

Verse 2
Isaiah 20:2. Go loose the sackcloth from off thy loins — By the sackcloth is meant either the hairy garment usually worn by the prophets, or a mournful habit, such as was commonly made of sackcloth which he wore in token of his grief for the great calamities that were already come upon Israel, and were coming on Judah. And he did so, walking naked and barefoot — Not wholly naked, but without his upper garment; as slaves and prisoners used to do, whose condition he was to represent. This action was both agreeable to the mode of instruction made use of in those times, and, as it was intended to excite the attention of the Israelites, was likewise very well adapted to promote that intention. — Vitringa.

Verses 3-6
Isaiah 20:3-6. And the Lord — Who here explains and applies the sign, said, Like as my servant hath walked naked, &c., three years — Not constantly, but when he went abroad among the people, to whom this was appointed to be a sign. Bishop Lowth says, probably three days, to show, that within three years the Egyptians and Ethiopians should be conquered and made captives by the king of Assyria, and be in the same condition, and that the town should be taken. But it is objected, that although a day is usually put for a year in the prophetic scriptures, a year is never put for a day. The former interpretation, therefore, is more probable. For a sign and wonder, &c. — Either when this judgment should come, namely, three years after this prophecy was thus uttered, or how long it should continue, namely, for three years: for some have observed, that the Assyrians spent so much time in conquering Egypt and Ethiopia. So shall the king of Assyria lead away the Egyptians — Like beasts, as ינהגis commonly used. And they shall be afraid and ashamed — Namely, all they that shall trust to them, and glory in them. In which words, “we have the consequence of the divine judgment upon the Egyptians and Ethiopians, and the scope of the prophecy, namely, to convince the inhabitants of Palestine, and among these some factious persons in Jerusalem, of the vanity of the confidence they placed in them; for when they should see the completion of this prophecy, they should then condemn their own folly for placing their expectations on so feeble a defence.” The inhabitant of this isle — Of this land, in which the prophet was, and to whose inhabitants these words were uttered. For the name of isles, or islands, is frequently given in Scripture, not only to lands encompassed with the sea, but also to such countries as were on the sea- coast, as Palestine or Canaan was. Shall say, Behold, such is our expectation — So vain is our hope, placed upon such a people as are unable to deliver themselves, and much more to deliver us: whither we flee for help — To whom we now and usually trust: and how shall we escape — Either by their help, who cannot defend themselves, or by our own strength, seeing they, who were much more potent than we are, could not escape?