In Oedipus Rex, hubris, or excessive pride, is a central theme that leads to the downfall of both Oedipus and Jocasta. This overconfidence blinds them to the truth and propels them towards their tragic fates. The play demonstrates the catastrophic consequences of human arrogance against divine will, as both characters attempt to defy the gods and alter their destinies.

Jocasta's hubris is evident in her belief that she can outsmart the gods. She and Laius receive a prophecy that their son will kill his father and marry his mother. In an attempt to thwart this fate, they send their son away to die. This act of defiance against the divine order is a display of supreme pride. Later, Jocasta publicly dismisses the power of prophecy, claiming that no human has skill in it:

All right, forget about those things you’ve said.           
      Listen to me, and ease your mind with this—
      no human being has skill in prophecy.

Her arrogance leads to her downfall when the truth of her marriage to her son is revealed, resulting in her shame and suicide.

Oedipus, too, is guilty of hubris. He believes he can escape the prophecy that he will kill his father and marry his mother. His rise to power as king of Thebes, after solving the Sphinx's riddle, fuels his arrogance. He declares his fame and determination to uncover the truth:

Here I am – myself – you all know me, the world knows my fame: I am Oedipus. 

His hubris blinds him to the reality of his actions and leads him to curse the murderer of Laius, not realizing he is condemning himself:

And on the murderer this curse I lay
(On him and all the partners in his guilt):--
Wretch, may he pine in utter wretchedness!
And for myself, if with my privity
He gain admittance to my hearth, I pray
The curse I laid on others fall on me.
See that ye give effect to all my hest,
For my sake and the god's and for our land,
A desert blasted by the wrath of heaven.

The irony of Oedipus's hubris is that his attempts to defy fate only ensure its fulfillment. His arrogance leads to his tragic realization and suffering, illustrating the Greek belief that humans cannot escape their destiny. The theme of hubris in Oedipus Rex serves as a powerful reminder of the dangers of excessive pride and the futility of challenging the divine order.