Ibn 'Abbas reported that the Messenger of Allah, may Allah bless him and grant him peace, went to visit a bedouin when he was ill and said, "Do not worry. It is a purification if Allah so wills." He said that the bedouin said, "It is a fever which boils in an old man and will cause him to visit the graves." "It is a blessing then," he concluded.  

أَنَّ رَسُولَ اللهِ ﷺ دَخَلَ عَلَى أَعْرَابِيٍّ يَعُودُهُ فَقَالَ لاَ بَأْسَ عَلَيْكَ طَهُورٌ إِنْ شَاءَ اللَّهُ قَالَ قَالَ الأعْرَابِيُّ بَلْ هِيَ حُمَّى تَفُورُ عَلَى شَيْخٍ كَبِيرٍ كَيْمَا تُزِيرُهُ الْقُبُورَ قَالَ فَنَعَمْ إِذًا