It is narrated from Hazrat Anas (may Allah be pleased with him) that whenever a man met the Prophet (peace and blessings be upon him), the Prophet (peace and blessings be upon him) would ask him, "How are you?" And he would always reply, "Alhamdulillah! I am well." The Prophet (peace and blessings be upon him) would respond, "May Allah keep you well." One day, when the Prophet (peace and blessings be upon him) met him, as usual, he asked him, "How are you?" He replied, "I am well, provided that I am grateful." Upon this, the Prophet (peace and blessings be upon him) remained silent. He asked, "O Messenger of Allah! Previously, when you would ask about my condition, you would pray for me, 'May Allah keep you well,' but today you remained silent?" The Prophet (peace and blessings be upon him) said, "Earlier, when I would ask you, you would say, 'Alhamdulillah! I am well,' so I would respond, 'May Allah keep you well.' But today you said, 'If I am grateful,' so I became doubtful, and thus I remained silent."