Albert Barnes Commentary Jeremiah 50:34

"Their Redeemer is strong; Jehovah of hosts is his name: he will thoroughly plead their cause, that he may give rest to the earth, and disquiet the inhabitants of Babylon." — Jeremiah 50:34 (ASV)

Redeemer—that is, גאל gā'al. Yahweh is Israel’s next relative, bound by law to avenge him, as well as to ransom him from captivity. It was the Go’el’s duty also to plead his kinsman’s cause. How thoroughly Yahweh will execute this duty for Israel is shown in the Hebrew by the triple repetition of the same word; literally “in pleading He will plead their plea.”

The land ...—Rather, “the earth.” Babylon has until now by its ambition kept the world in unrest: now by its fall men everywhere can dwell in security.