Jamieson, Fausset and Brown on Jeremiah 50:34

34. strong--as opposed to the power of Israel's oppressor (Re 18:8).

plead ... 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 (Mi 7:9; Zec 3:1-5; 1Jo 2:1).

give rest ... disquiet--There is a play on the similarity of sounds in the two Hebrew verbs 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) (Is 14:6-8).