Adam Clarke on Jeremiah 12:1

Righteous art thou, O Lord, when I plead with thee - The prophet was grieved at the prosperity of the wicked; and he wonders how, consistently with God's righteousness, vice should often be in affluence, and piety in suffering and poverty. He knows that God is righteous, that every thing is done well; but he wishes to inquire how these apparently unequal and undeserved lots take place. On this subject he wishes to reason with God, that he may receive instruction.