Macbeth kills the two drunken guards in a rage, claiming that it was them that had killed King Duncan, as they were covered in the king's blood. This happens in Act II, Scene III in William Shakespeare's tragedy, "Macbeth."
After Macbeth kills King Duncan, in a fever of guilt, he brings the daggers he used to kill the king back to his chambers. Lady Macbeth demanded that Macbeth return to the scene and place the daggers in Duncan's room. He refuses to, so Lady Macbeth describes him as "infirm of purpose" and takes them herself. Lady Macbeth smears blood on the faces of the guards to implicate them in the murder and then returns to her room, claiming that "A little water clears us of this deed."