There isn't necessarily a logical reason for the fear, but then fear is not a logical thing. Although Macbeth says, "My fears in Banquo stick deep," he is not totally clear about why he is afraid of him.
Most likely, he is afraid that Banquo knows too much about him, knows what the witches said to him and how troubled he was by it, and as a result may suspect Macbeth of murdering Duncan.
He is also annoyed by the prophecy of the "fruitless crown" and the prophecy that Banquo will be the father to kings. To prevent this, Macbeth would have to kill not only Fleance but also Banquo, to prevent Banquo from fathering more children. This prophecy does not threaten Macbeth, yet he feels threatened by it.
when macbeth visits the witches the second time, which noble do they say he should fear
Macbeth becomes jealous of Banquo because he feels threatened by the witches' prophecy that Banquo's descendants will be kings, leading Macbeth to fear that Banquo's lineage will jeopardize his own power and position as king. Macbeth's increasing paranoia and ambition drive him to eliminate Banquo and his son in order to secure his hold on the throne.
She is old
"Out, damned spot!" from Shakespeare's "Macbeth" alludes to the fear and guilt that Lady Macbeth experiences. "Courage is not the absence of fear, but the triumph over it." - Nelson Mandela's quote alludes to the idea that fear can be overcome through bravery and determination.
She is afraid that Macbeth, being a careful and cautious man, will estimate that the potential benefits of becoming king are not a good enough reason to kill Duncan. Her plan is to put pressure on him to commit the murder.
No logical reason, but then fear is not a logical thing. Although Macbeth says, "My fears in Banquo stick deep," he is not totally clear about why he is afraid of him. Most likely, he is afraid that Banquo knows too much about him, knows what the witches said to him and how troubled he was by it, and as a result may suspect Macbeth of murdering Duncan. He is also annoyed by the prophecy of the "fruitless crown" and the prophecy that Banquo will be the father to kings. To prevent this, Macbeth would have to kill not only Fleance but also Banquo, to prevent Banquo from fathering more children. This prophecy does not threaten Macbeth, yet he feels threatened by it. All of this makes the ball of anxiety which he feels because of the murder focus irrationally on Banquo.
Macbeth is afraid of the dark because it represents the unknown and allows room for his guilt and paranoia to manifest. The darkness symbolizes the moral turmoil he is facing and his fear of being exposed for his wrongdoings. Additionally, the dark is often associated with evil in the play, reflecting Macbeth's own descent into darkness and deception.
Probably courage most distinguishes him at the beginning of the play. As he commits the murder, though, he starts to lose it and begins to be governed by fear. He murders the grooms out of fear.
she warns her husband to disguise his fear and deceit
his mind will never full with falter and fear
beacuse he has haith in the witches' prophecies
When Macbeth meets with the two down and men is the moment in act three that manhood is equated with a lack of fear. Here is where Macbeth questions there manhood.