The witches, used throughout Macbeth to foreshadow the events in the play, essentially tell Banquo that he will be less than Macbeth, but greater that he will be not as happy as Macbeth yet much happier and that he will be king even though there will be no king.
The witches gather on the moor and cast a spell as Macbeth and Banquo arrive. The witches hail Macbeth first by his title Thane of Glamis, then as Thane of Cawdor and finally as king. They then prophesy that Banquo's children will become kings.
