He’s here in double trust;
First, as I am his kinsman and his subject,
Strong both against the deed; then, as his host,
Who should against his murderer shut the door,
Not bear the knife myself.

– William Shakespeare

Macbeth, Act 1, Scene 7. Macbeth is having second thoughts about murdering Duncan in his bed while a guest at Macbeth’s palace. Despite his hunger for power, his conscience and sense of morality still seem to be working. With some irony, he says that as the King’s kinsman and host, he should be the one protecting him from the “murderer,” instead of killing him.