Oedipus is genuinely concerned by the damage the plague is doing to his people and seeks to help. Creon informs him that the plague is the result of King Laius's murder and that the murderer must be found and killed or expelled. Oedipus seeks counsel from Teiresias the prophet. However, the prophet is afraid of divulging the truth about the situation. He knows that Oedipus unknowingly killed the king, his own father, and married his own mother, making him directly responsible for the plague.
Teiresias tries to dissuade Oedipus from seeking the truth, which is clearly more than he can bear, but Oedipus goads Teiresias into talking. He is angered at what he discovers, but his anger is directed at Teiresias and Creon because he believes they are reaching for his throne. Creon tells Oedipus that his temper is his worst enemy.
I'll go, and they have known my innocence. Your temper is your own worst enemy
However, the truth is still revealed to Oedipus by credible sources. Although Oedipus' fate is already sealed at birth, some suggest that if he had not killed his father then tragedy would not have befallen him. Oedipus's actions are fueled by anger and although he had a right to feel aggrieved when the king's servant forcefully pushed him out of the way, Oedipus overreacted by killing almost all of the men out of anger.
The one who led the way, and the old man himself, wanted to push me out of the road by force. I became angry and struck the coachman who was pushing me.
Oedipus suffers from deep-seated hubris that causes him to overreact out of anger. Thus, his anger is preceded by his pride, making pride his strongest flaw.