Macbeth meets Banquo, where Banquo mentions his dreams of the witches Macbeth lies, saying he has not thought of them, and offers to talk about them later. This lie begins Macbeths betrayal of Banquo
I think not of them. Yet, when we can entreat an hour to serve, we would spend it in some words upon that business.
I dreamt last night of the Weird Sisters. To you they have showed some truth.
Macbeth sees a floating dagger in front of him. He wonders if it is just a vision from his worried mind, dismissing the dagger and preparing himself for the task ahead
Macbeth returns from killing Duncan as a nervous wreck, hallucinating knocking. An angry Lady Macbeth calls him weak, and realizes that Macbeth did not plant the bloody daggers to avoid blame, and she must go fix his mistake.