Their Redeemer is strong; the LORD of hosts is his name: he shall throughly plead their cause, that he may give rest to the land, and disquiet the inhabitants of Babylon.
Their Redeemer is strong - as opposed to the power of Israel's oppressor (Revelation 18:8).
He shall throughly plead their cause - as their advocate. Image from a court of justice: appropriate, as God delivers His people not by mere might, but by righteousness. His plea against Satan and all their enemies is His own everlasting love, reconciling mercy and justice in the Redeemer's work and person (Micah 7:9; Zechariah 3:1-5; 1 John 2:1).
That he may give rest to the land, and disquiet ... Babylon. There is a play on the similarity of sounds in the two Hebrew verbs х hirgiya` (H7280) ... wªhirgiyz (H7264)], to express more vividly the contrast; 'that He may give quiet to the land of Judah (heretofore disquieted by Babylon); but disquiet to the inhabitants of Babylon (heretofore quietly secure)' (Isaiah 14:6-8).