Isaiah 20

20:1. In the year 711 BC, Sargon, King of Assyria, attacked and captured Ashdod, putting down a revolt inspired by Egypt. Ashdod was one of five main Philistine cities and was located on the Via Maris (Way of the Sea), which connected Mesopotamia and Egypt along the Mediterranean Coast.

20:2. At that time, the Lord did speak through Isaiah and said to him (as recorded in the Dead Sea Scrolls), “Go and loose the sackcloth from off thy loins, and put off thy shoes from thy foot. And he did so, walking naked and barefoot.”

20:2–3. In verse 3, he says directly that he was to be a sign for three years against Egypt and Cush and that the King of Assyria would lead away Egyptians and Cushites stripped and barefoot.

So the Lord had spoken through Isaiah, son of Amoz, fulfilling the prophecy given in Isaiah 8:18:

Behold, I and the children whom the Lord hath given me are for signs and for wonders in Israel from the Lord of hosts, which dwelleth in mount Zion.