For thus saith the Lord GOD, My people went down aforetime into Egypt to sojourn there; and the Assyrian oppressed them without cause.
My people - Jacob and his sons.
Went down aforetime into Egypt. Judea was an elevated country compared with Egypt.
To sojourn there. They went there to stay only until the famine in Canaan should have ceased.
And the Assyrian oppressed them without cause - Sennacherib. Remember how I delivered you from Egypt and the Assyrian; what, then is to prevent me from delivering you out of Babylon (and the mystical Babylon and Antichrist in the last days)?
Without cause - answering to "for nought" in Isaiah 52:5: it was an act of gratuitous oppression in the present case, as in that case.