The Tragedy of Macbeth — Act 2, Scene 2: The same.

Lady Macbeth waits outside after giving Macbeth the chance to kill Duncan, and she hears the drugged grooms asleep while the owl cries in the night. Macbeth returns shaken and says he has done the murder. He reports hearing noises and voices that seemed to wake the sleeping men, and he is horrified that he could not say a blessing after the deed. He fixates on the idea that he has murdered sleep itself. Lady Macbeth stays practical, tells him not to dwell on it, and orders him to return the daggers so she can smear the sleeping grooms with blood. As knocking sounds through the castle, Macbeth is overwhelmed by guilt and dread.