Macbeth looks on the blood on his hands and says that he could not utter "Amen" when he heard the two men praying after one wakened from a hideous dream of murder. He has brought the grooms' daggers from Duncan's room and as he dare not take them back, Lady Macbeth does so. Immediately after the murder, Macbeth realises that he can never again have the comfort of prayer and the balm of sleep. Lady Macbeth knows that they must not admit such thoughts; "so it will make us mad". When he is afraid to return, she scorns him as "infirm of purpose" and is able to make a grim joke: she will gild the faces of the grooms with blood so that the guilt may seem to be theirs. While Macbeth is so unnerved that he cannot bear the knocking, Lady Macbeth takes charge.
