Because they do things in threes. They had three prophecies for Macbeth and now they have three for Banquo.
He dreamed of the three witches, and then confided in Macbeth about his dreams. Macbeth replied that he hadn't thought of the three weird sister, which was a lie.
Macbeth kills Banquo in the play and then Banquo's ghost haunts Macbeth.
In Shakespeare's "Macbeth," the witches tell Banquo that he will be "lesser than Macbeth, and greater," implying that while he won't achieve the same level of power as Macbeth, he will be more morally upright. They also prophesy that his descendants will be kings, suggesting that although Banquo himself may not attain the throne, his lineage will eventually rule. This duality highlights the contrast between Banquo's integrity and Macbeth's ambition.
Because Macbeth is planning to kill Banquo and Fleance. Banquo states that none of Macbeth's family would be next in line for King but his family will. Macbeth sees the three witches to check that what Banquo was saying is correct.
Macbeth's best friend was Banquo. They fought together in battle before Macbeth's rise to power.
Macbeth sees the ghost of the recently murdered Banquo.
Macbeth kills Banquo in the play and then Banquo's ghost haunts Macbeth.
No, Lady Macbeth is not aware that Macbeth has planned the death of Banquo and Fleance.
Macbeth's soldiers do not kill Banquo, Macbeth hires three murderers to do the job.
In Act 3 of Macbeth, Macbeth becomes suspicious that Banquo poses a threat to his throne. He worries that Banquo's descendants will inherit the crown, as the witches prophesied. This suspicion leads Macbeth to plot Banquo's murder.
*Banquo. Macbeth's best friend is Banquo, but he is also Macbeth's enemy. After the meeting with the witches, Macbeth finds out that he will become the Thane of Cawdor and the King of Scotland. Eventually, he achieves both of these prophecies. Banquo, Macbeth, and Lady Macbeth are the only people that know about the witches. Banquo becomes suspicious of Macbeth because Macbeth fulfills the prophecy after King Duncan is murdered, and Macbeth acknowledges this fact. Basically, Macbeth doesn't trust Banquo.