Thou has it no king, Cawdor, Glamis, all. As the weird women promised, and I fear Thou played’st most foully for ‘t. Yet it was said It should not stand in thy posterity, But that myself should be the root and father Of many kings. If there come truth from them – As upon thee, Macbeth, their speeches shine – Why, by the verities on thee made good, May they not be my oracles as well, And set me up in hope? But hush, no more.
In Act 3, scene 1, Banquo’s soliloquy reveals that he is suspicious of Macbeth, who, in becoming king, has achieved all that the Witches promised for him. Banquo senses that Macbeth engaged in foul play in order to make the Witches’ prophecy come true. While the idea that Macbeth may have murdered Duncan fills Banquo with fear, the thought also gives Banquo hope that what the Witches predicted for him will come true. He doesn’t realize that in order for his sons to become king, he will have to die.