Final answer:
Banquo is suspicious about Macbeth and is buying into what the witches said.
Step-by-step explanation:
In Act 3, Scene 1 of the play Macbeth, Banquo is suspicious about Macbeth and is also buying into what the witches said. This can be seen in the lines:
"Banquo. What, can the devil speak true?" (Act 3, Scene 1)
"Banquo. Look, how our partner's rapt." (Act 3, Scene 1)
"Banquo. Were such things here as we do speak about? Or have we eaten on the insane root That takes the reason prisoner?" (Act 3, Scene 1)
These lines show Banquo's suspicion towards Macbeth and his belief in the witches' prophecies.