What are some significant quotes from Oedipus Rex?

One massively important quotation is Teiresias's revelation of truth to Oedipus.  The blind prophet, who Oedipus has called, tells the king

Hear then: this man whom thou hast sought to arrestWith threats and warrants this long while, the wretchWho murdered Laius -- that man is here.He passes for an alien in the landBut soon shall prove a Theban, native born.And yet his fortune brings him little joy;For blind of seeing, clad in beggar's weeds,For purple robes, and leaning on his staff,To a strange land he soon shall grope his way.And of the children, inmates of his home,He shall be proved the brother and the sire,Of her who bare him son and husband both,Co-partner, and assassin of his sire.Go in and ponder this, and if thou findThat I have missed the mark, henceforth declareI have no wit nor skill in prophecy.

Oedipus has angered and insulted Teiresias enough that the prophet tells the king the truth from which he once sought to protect him.  Teiresias knows that the truth will only cause pain and misery, but when Oedipus rashly and angrily accuses the old prophet of colluding with Creon, who is brother-in-law (and uncle), Teiresias finally tells Oedipus what he knows (though he doesn't tell Oedipus that the person he speaks of is actually the king himself; he leaves Oedipus to discover that awful nugget for himself).  What he tells Oedipus is that the man he seeks, the killer of Laius, is actually there, in Thebes, and that people think he is a foreigner when, in fact, he was born in Thebes.  Furthermore, this man has married his mother and sired children by her.  Soon this man will learn the truth of his life and he will be cast out of Thebes, blind, and clothed only in rags.  Teiresias finishes by saying, essentially, "and if it turns out I'm wrong, then you can tell everyone that I am a terrible seer and lack skill in prophecy."  Not only does Teiresias know the past then, but he sees Oedipus's tragic and lonely future as well.
Another important line comes from the lips of Oedipus's wife (and mother), Jocasta.  In an effort to soothe and assure him, she tells him that no mortal really has the gift of prophecy, and she says,

An oracleOnce came to Laius [...] declaring he was doomedTo perish by the hand of his own son [...].Now Laius -- so at least report affirmed --Was murdered on a day by highwaymen,No natives, at a spot where three roads meet.As for the child, it was but three days old,When Laius, its ankles pierce and pinnedTogether, gave it to be cast awayBy others on the trackless mountain side.

However, in seeking to reassure Oedipus, Jocasta actually provides the detailed information that will prove Oedipus to be the son of her and Laius.  Oedipus himself will recall that he met and killed an old man at the meeting of three roads, and a shepherd will later reveal that he took the baby with its feet pinned together and gave it to the couple Oedipus knows as his parents.  Ironically, in her attempt to calm Oedipus, she actually helps to reveal the truth that will ruin them both.