Albert Barnes Commentary Jeremiah 4:7

"A lion is gone up from his thicket, and a destroyer of nations; he is on his way, he is gone forth from his place, to make thy land desolate, that thy cities be laid waste, without inhabitant." — Jeremiah 4:7 (ASV)

Rather, A “lion”... a “destroyer” of nations: a metaphor descriptive of the impending calamity. A lion is just rousing himself from his lair, but no common one. It is destroyer, not of men, but of nations.

Is on his way - literally, “has broken up his encampment.” Jeremiah uses a military term strictly referring to the striking of tents in preparation for the march.

Without an inhabitant - The final stage of destruction, actually reached in the utter depopulation of Judaea consequent upon Gedaliah’s murder.