Adam Clarke on Joel 3

The valley of Jehoshaphat - There is no such valley in the land of Judea; and hence the word must be symbolical. It signifies the judgment of God, or Jehovah judgeth; and may mean some place (as Bp. Newcome imagines) where Nebuchadnezzar should gain a great battle, which would utterly discomfit the ancient enemies of the Jews, and resemble the victory which Jehoshaphat gained over the Ammonites, Moabites, and Edomites, 2Chr 20:22-26.

And parted my land - The above nations had frequently entered into the territories of Israel; and divided among themselves the lands they had thus overrun.

While the Jews were in captivity, much of the land of Israel was seized on, and occupied by the Philistines, and other nations that bordered on Judea.

Have given a boy for a harlot - To such wretched circumstances were the poor Jews reduced in their captivity, that their children were sold by their oppressors; and both males and females used for the basest purposes. And they were often bartered for the necessaries or luxuries of life. Or this may refer to the issue of the Chaldean war in Judea, where the captives were divided among the victors. And being set in companies, they cast lots for them: and those to whom they fell sold them for various purposes; the boys to be slaves and catamites, the girls to be prostitutes; and in return for them they got wine and such things. I think this is the meaning of the text.

What have ye to do with me - Why have the Syrians and Sidonians joined their other enemies to oppress my people? for they who touch my people touch me.

Will ye render me a recompense? - Do you think by this to avenge yourselves upon the Almighty? to retaliate upon God! Proceed, and speedily will I return your recompense; I will retaliate.

Ye have taken my silver and my gold - The Chaldeans had spoiled the temple, and carried away the sacred vessels, and put them in the temple of their own god in Babylon.