Isaiah 20:2-4

at the same time spake the LORD by Isaiah the son of Amoz, saying, Go and loose the sackcloth from off thy loins, and put off thy shoe from thy foot. And he did so, walking naked and barefoot. And the LORD said, Like as my servant Isaiah hath walked naked and barefoot three years for a sign and wonder upon Egypt and upon Ethiopia; so shall the king of Assyria lead away the Egyptians prisoners, and the Ethiopians captives, young and old, naked and barefoot, even with their buttocks uncovered, to the shame of Egypt.