Answer: 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
Explanation: In Act I, Scene VII, of "The Tragedy of Macbeth", by William Shakespeare the lines that show that Macbeth is aware that the crime he intends to commit goes against loyalty and hospitality are mentioned above. He says that as subject to the King he cannot kill him because he owes him his loyalty. Secondly as his host, due to hospitality, he should care for his safety instead of killing him.