BANQUO: I dreamt last night of the three weird sisters:
To you they have show’d some truth.
MACBETH: I think not of them.

– William Shakespeare

Macbeth, Act 2, Scene 1. Banquo admits that he has been thinking of the Witches and their prophecies. But Macbeth lies and says that he doesn’t think of them at all. This is an example of dramatic irony, since the audience knows that Macbeth has been thinking of nothing else but the Witches’ prediction that he will be king.