Job 15:20 - Joseph Benson’s Commentary on the Old and New Testaments

The wicked man travaileth with pain That is, lives a life of care, and fear, and grief, by reason of God's wrath, the torments of his own mind, and his outward calamities. The number of his years is hidden He knows not how short the time of his life is, and therefore lives in continual fear of losing it. To the oppressor To the wicked man: he names this one sort of them, because he supposed Job to be guilty of this sin; and in opposition to what Job had affirmed of the safety of such persons, Job 12:6, and because such are apt to promise themselves a longer and happier life than other men.