In Sophocles Oedipus Rex, dramatic irony is often present in Oedipus long speeches. Oedipus constantly sees things incorrectly, and is in denial that he has, in fact, killed his father and married his mother. This is first apparent when he demands the death of the man who killed Laios. Oedipus calls the man who did this an evil murder. Oedipus assumes that, as he became a citizen of Thebes after the murder, though he did kill someone, he is ruled out as a suspect of Laios assassin. In another speech, Oedipus accuses Creon of setting him up in order to get the throne, by framing him as the murderer.
At this point, Oedipus is in denial that he is guilty, even though all of the evidence points to him. In reality, Creon does not want to be king at all; he enjoys his current position of wealth and power without any real responsibility. A third occasion of irony in the speeches is Oedipuss firm belief that the people who raised him were his biological parents. Oedipus refuses to believe that Iocaste is his mother, and that by escaping to Thebes, he did not escape the fate he was told of at Delphi. Because of Oedipuss denial and stubbornness, he did suffer greatly and commit the greatest sin.