Ibn 'Abbas reported that the Prophet ﷺ went to visit a bedouin who was ill. When the Prophet ﷺ visited someone who was ill, he would say, 'There is no harm in it. It is a purification, Allah willing." That man then said, "A purification! No, rather it is a fever which boils (or appears) in an old man and will cause him to visit the graces." The Prophet ﷺ said, "Then yes (it is)".

حَدَّثَنَا مُعَلَّى، قَالَ: حَدَّثَنَا عَبْدُ الْعَزِيزِ بْنُ الْمُخْتَارِ، قَالَ: حَدَّثَنَا خَالِدٌ، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ، أَنَّ النَّبِيَّ ﷺ دَخَلَ عَلَى أَعْرَابِيٍّ يَعُودُهُ، قَالَ: وَكَانَ النَّبِيُّ ﷺ إِذَا دَخَلَ عَلَى مَرِيضٍ يَعُودُهُ قَالَ: لاَ بَأْسَ طَهُورٌ إِنْ شَاءَ اللَّهُ، قَالَ: ذَاكَ طَهُورٌ، كَلاَّ بَلْ هِيَ حُمَّى تَفُورُ، أَوْ تَثُورُ، عَلَى شَيْخٍ كَبِيرٍ، تُزِيرُهُ الْقُبُورَ، قَالَ النَّبِيُّ ﷺ: فَنَعَمْ إِذًا.