Isaiah 20:3
"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;"
Cross References (ranked by relevance)
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.
And he heard say concerning Tirhakah king of Ethiopia, He is come forth to make war with thee. And when he heard it, he sent messengers to Hezekiah, saying,
After the number of the days in which ye searched the land, even forty days, each day for a year, shall ye bear your iniquities, even forty years, and ye shall know my breach of promise.
For I am the LORD thy God, the Holy One of Israel, thy Saviour: I gave Egypt for thy ransom, Ethiopia and Seba for thee.