In an instance of both foreshadowing and dramatic irony, Tiresias concludes his argument with Oedipus by giving in to Oedipus's demands and providing his full insight as prophet:
he soon will be revealed a native Theban
but he will take no joy in the revelation.
Blind who now has eyes, beggar who now is rich,
he will grope his way toward a foreign soil,
a stick tapping before him step by step.
[...]
Revealed at last, brother and father both
to the children he embraces, to his mother
son and husband both—he sowed the loins
his father sowed, he spilled his father’s blood!
This is neither the first nor the last time in Oedipus Rex where the end of the play is articulated by a character for the audience to hear. It is, however, a particularly complete instance of foreshadowing, as the entire conclusion of the play is described in somewhat explicit terms by Tiresias.
It is also a moment of dramatic irony, as the reader knows the subject of Tiresias's prophecy is Oedipus, while Oedipus himself is unaware of this fact. The ironic disconnect between the reader's awareness and Oedipus's knowledge is established relatively early in the play, creating a tension that builds with the story. The dramatic irony figuratively mimics Oedipus's blindness to the truth of the prophecy: Oedipus is "blind" yet "now has eyes," both in the sense that he has yet to literally blind himself, but also in the sense that he cannot yet see the truth of what Tiresias is saying. Oedipus Rex is one of the best examples of dramatic irony across literature, and Sophocles uses it heavily throughout the story.