"Is this a dagger which I see before me?" The dagger pointing to Duncan's room is the sign he sees.
He sees a vision of a bloody dagger, leading him to Duncan.
The ghost of his dead father
Macbeth believes he has to kill Duncan's guards in case they heard anything happen in the room while Macbeth was killing Duncan.
And then Macbeth asked Macbeth if he confronted Macbeth on killing Macbeth with Macbeth.
The king
The reaction between Lady Macbeth and Macbeth is initially very different after they kill Duncan. Lady Macbeth is enthusiastic but Macbeth regrets his actions.
"Sleep no more, Macbeth doth murder sleep."
Lady Macbeth convinces Macbeth to kill Duncan by questioning his masculinity and invoking his ambition for power. She manipulates him into believing that murdering Duncan is the only way to achieve their goal of becoming king and convinces him that they can get away with it.
Macbeth believes he has to kill Duncan's guards in case they heard anything happen in the room while Macbeth was killing Duncan.
Lady Macbeth talked Macbeth into killing his cousin, King Duncan of Scotland, who was a guest in his house at the time.
And then Macbeth asked Macbeth if he confronted Macbeth on killing Macbeth with Macbeth.
The king
In Shakespeare's play "Macbeth," the idea that people should be killed originates primarily from Lady Macbeth. She is the one who convinces Macbeth to kill King Duncan in order to fulfill the witches' prophecy and secure his place as king.
The reaction between Lady Macbeth and Macbeth is initially very different after they kill Duncan. Lady Macbeth is enthusiastic but Macbeth regrets his actions.
Killing him in his sleep. Scandalous!
She talks her husband into killing Duncan.
The witches don't make Macbeth perform any dark acts, such as killing King Duncan; they just put the idea in his head. The witches tell Macbeth he is the Thane of Cawdor (which he doesn't know yet) and also tell him that he will be king. Once Macbeth finds out he is in fact the Thane of Cawdor, he begins to believe the witches' prophecies. Lady Macbeth convinces him that the only way Macbeth can be king is by killing King Duncan, and he does so. The witches' role in making Macbeth a tragic hero is to serve a catalyst for Macbeth's dark thoughts.
"Sleep no more, Macbeth doth murder sleep."
Macbeth was not a vassal of King Duncan. Macbeth's act of killing King Duncan would be considered regicide because he unlawfully killed his king, who was his sovereign and ruler.