went down - Judea was an elevated country compared with Egypt.
sojourn - They went there to stay only till the famine in Canaan should have ceased.
Assyrian - 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 the Antichrist in the last days)?
without cause - answering to “for naught” in Isa 52:5; it was an act of gratuitous oppression in the present case, as in that case.