Final answer:
Jokasta tells Oedipus that the Oracle had prophesied that Laois would be killed by his own son, a prophecy she believed to have failed as she thought Laois was killed by bandits.
Step-by-step explanation:
According to Jokasta in the play by Sophocles, the Oracle made a prophecy to Laois that he would be killed by his own son. Jokasta uses this as an example to persuade Oedipus not to worry about prophecies, as she incorrectly believes that Laois was killed by bandits at a crossroad, not by his son as foretold. This revelation deeply disturbs Oedipus, who has been trying to avoid the fate predicted for him by another Oracle of Delphi, which was that he would kill his father and marry his mother.
The tragic irony lies in the attempt to avert destiny, only to unknowingly contribute to its fulfillment. This prophecy serves as a pivotal element in the unfolding tragedy, highlighting the inescapable and tragic nature of the events in the play.