Charles Ellicott Commentary Isaiah 20:3

"And Jehovah said, Like as my servant Isaiah hath walked naked and barefoot three years for a sign and a wonder concerning Egypt and concerning Ethiopia;" — Isaiah 20:3 (ASV)

For a sign and wonder upon Egypt and upon Ethiopia. —Apparently Isaiah prophesied in act, but in silence, and did not unfold the meaning of the symbol till the three years came to an end. There are no adequate grounds for limiting his dramatic action to a single day or three days. Egypt and Ethiopia are, as in Isaiah 18; Isaiah 19, closely connected, both countries being under a king of Ethiopian origin, Sabaco.