Bukhari :: Book 7 :: Volume 70 :: Hadith 560

Narrated Ibn Abbas:

The Prophet went to visit a sick bedouin. Whenever the Prophet went to a patient, he used to say to him, "Don't worry, if Allah will, it will be expiation (for your sins):" The bedouin said, "You say expiation? No, it is but a fever that is boiling or harassing an old man and will lead him to his grave without his will." The Prophet said, "Then, yes, it is so."

Source materials are from the University of Southern California MSA site
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