Sahih Bukhari
Patients
Volume: 007 / Book Number: 070 / Hadith Number: 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."