Macbeth kills Duncan and says that his hands will be permanently stained from his blood, meaning
that he can never be forgiven for this deed. After
he kills Duncan, Macbeth feels like he's crossed a
line and might as well continue to do evil things
because he's already evil now. What do you think
about his logic?

lady Macbeth is the one who force Macbeth to kill Duncan

Explanation:

Macbeth was a very good person in the very beginning of the story, later on his mind was changed by lady Macbeth and the three witches. He believe lady Macbeth blindfold. Even though at the beginning he refuses lady Macbeth's word to kill Duncan but later on his bind was changed by lady Macbeth and she forced Macbeth to kill Duncan. After killing Duncan he displaced all the evidence including washing his body. How much he clean his hand he feels that he can still be smell the smell of Duncan's blood that's why he said

"be permanently stained from his blood."