It is narrated from Hazrat Aisha (may Allah be pleased with her) that the Prophet (peace and blessings be upon him) used to say to her: "When you are angry, I can tell that you are angry, and when you are pleased, I can tell that as well." She asked, "O Messenger of Allah! How do you know this?" The Prophet (peace and blessings be upon him) replied, "When you are angry, you say 'O Muhammad,' and when you are pleased, you say 'O Messenger of Allah.'"