Narrated Ibn 'Abbas:

Allah's Apostle entered upon a sick bedouin in whom he went to visit and said to him, "Don't worry, Tahur (i.e., your illness will be a means of cleansing of your sins), if Allah Will." The bedouin said, "Tahur! No, but it is a fever that is burning in the body of an old man and it will make him visit his grave." The Prophet ﷺ said, "Then it is so."

حَدَّثَنَا مُحَمَّدٌ، حَدَّثَنَا عَبْدُ الْوَهَّابِ الثَّقَفِيُّ، حَدَّثَنَا خَالِدٌ الْحَذَّاءُ، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ أَنَّ رَسُولَ اللَّهِ ﷺ دَخَلَ عَلَى أَعْرَابِيٍّ يَعُودُهُ فَقَالَ " لاَ بَأْسَ عَلَيْكَ طَهُورٌ، إِنْ شَاءَ اللَّهُ ". قَالَ قَالَ الأَعْرَابِيُّ طَهُورٌ، بَلْ هِيَ حُمَّى تَفُورُ عَلَى شَيْخٍ كَبِيرٍ، تُزِيرُهُ الْقُبُورَ. قَالَ النَّبِيُّ ﷺ " فَنَعَمْ إِذًا ".