Virtues and Merits of the Prophet (pbuh) and his Companions

Bukhari :: Book 4 :: Volume 56 :: Hadith 813

Narrated Ibn 'Abbas:

The Prophet paid a visit to a sick bedouin. The Prophet when visiting a patient used to say, "No harm will befall you! May Allah cure you! May Allah cure you!" So the Prophet said to the bedouin. "No harm will befall you. May Allah cure you!" The bedouin said, "You say, may Allah cure me? No, for it is a fever which boils in (the body of) an old man, and will lead him to the grave." The Prophet said, "Yes, then may it be as you say."