What Macbeth and Banquo discuss in Act II, Scene 1:

Banquo, who has come to Inverness with Duncan, wrestles with the witches' prophecy. He must restrain himself the “cursed thoughts” that tempt him in his dreams (II i 8). When Banquo raises the topic of the prophecy as Macbeth enters the scene, Macbeth pretends that he has given little thought to the witches' prophesy.