Hamlet's three scenes progressing to his killing Claudius.
Act 1, Scene 5
You should know, my noble son, the real snake that stung your father is now wearing his crown.
My uncle? I knew it! I swear that I will wrest retribution from Claudius. I will remember you.
Act 3, Scene 3
I could do it easily now, but if a villain kills my father, then I can not send that same villain to Heaven.
My guilt is even stronger than my intentions. So, I'll pray for God's mercy.
Act 5, Scene 2
The blade is poisoned, so get to work poison. And here you Danish murderer, drink this. Follow my mother.
King Hamlet's ghost visits Hamlet and confirms the prince's suspicion that Claudius murdered the late King. Hamlet vows to avenge and honor his father by killing Claudius.
Hamlet sees Claudius alone and recognizes it as the perfect opportunity to kill him, but stops. Because Claudius is praying for forgiveness, Hamlet knows that by killing Claudius now, he would send the King straight to heaven.
To kill Hamlet, Clausius poisons his goblet and Laertes's rapier, but Gertrude drinks instead. Hamlet discovers Clausius's treason and finally kills the King, stabbing Claudius with the rapier and making him also drink the poison.