The Tragedy of Macbeth — Act 1, Scene 7: Macbeth's castle.

In Macbeth’s castle, Macbeth is alone and struggles with the murder of Duncan in a long private speech. He weighs the act against its consequences, knowing Duncan is his king, kinsman, and guest, and he recognizes that only ambition is pushing him forward. Lady Macbeth enters and finds him hesitating because Duncan is nearly finished supper. Macbeth says he will not continue, but Lady Macbeth mocks his courage and questions his manhood until she overpowers his doubts. She then explains her plan to get Duncan’s chamberlains drunk, so Macbeth can blame them after the murder. Macbeth agrees, and they leave determined to hide their purpose behind a welcoming face.