Job has proclaimed his innocence throughout the book, convinced that he does not deserve what has happened to him. Here, at the end of his final monologue, he grants that he may be guilty of something, but he does not know what it is.
The retributive system still dominates Job’s thinking about why people suffer. Good people should not have to endure the kind of pain that he has experienced. Tragedies should only come to those who deserve them. Job’s friends have tried desperately to find some sin in Job that would justify his suffering as punishment. Job has reacted by claiming to be innocent and, therefore, Job blames God for abandoning God’s own system of justice.
In spite of his insistence that he is innocent, Job, in this passage, admits that he may have done something terrible, something worthy of such treatment by God, but he does not know what it could be. If only God would tell him! A defendant should have the right to hear the charges against him. Up to now, God has been silent. If he only knew his fault, Job would not be ashamed to admit it. But he cannot confess to a crime that he does not think he has committed.