what thoughts does banquo reveal at the start of act 3

Alone at Macbeth's court, Banquo voices his suspicions that Macbeth has killed Duncan in order to fulfill the witches' prophesies. He thinks that Macbeth has done something bad to get his kingship. He also muses that perhaps the witches' vision for his own future will also be realized, but pushes the thought from his mind.