Adam Clarke on Job 15:20

The wicked man travaileth with pain - This is a most forcible truth: a life of sin is a life of misery; and he that Will sin Must suffer. One of the Targums gives it a strange turn: - "All the days of the ungodly Esau, he was expected to repent, but he did not repent; and the number of years was hidden from the sturdy Ishmael." The sense of the original, מתחולל mithcholel, is he torments himself: he is a true heautontimoreumenos, or self-tormentor; and he alone is author of his own sufferings, and of his own ruin.