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كتاب المرضى
75  
Patients
(16)
Chapter: To say "I am sick," or "Oh, my head!" or "My ailment has been aggravated"
(16)
باب قَوْلِ الْمَرِيضِ إِنِّي وَجِعٌ أَوْ وَارَأْسَاهْ، أَوِ اشْتَدَّ بِي الْوَجَعُ
Sahih al-Bukhari 5667

Narrated Ibn Mas`ud:

I visited the Prophet (ﷺ) while he was having a high fever. I touched him an said, "You have a very high fever" He said, "Yes, as much fever as two me of you may have." I said. "you will have a double reward?" He said, "Yes No Muslim is afflicted with hurt caused by disease or some other inconvenience, but that Allah will remove his sins as a tree sheds its leaves."

حَدَّثَنَا مُوسَى، حَدَّثَنَا عَبْدُ الْعَزِيزِ بْنُ مُسْلِمٍ، حَدَّثَنَا سُلَيْمَانُ، عَنْ إِبْرَاهِيمَ التَّيْمِيِّ، عَنِ الْحَارِثِ بْنِ سُوَيْدٍ، عَنِ ابْنِ مَسْعُودٍ ـ رضى الله عنه ـ قَالَ دَخَلْتُ عَلَى النَّبِيِّ صلى الله عليه وسلم وَهْوَ يُوعَكُ فَمَسِسْتُهُ فَقُلْتُ إِنَّكَ لَتُوعَكُ وَعْكًا شَدِيدًا‏.‏ قَالَ ‏"‏ أَجَلْ كَمَا يُوعَكُ رَجُلاَنِ مِنْكُمْ ‏"‏‏.‏ قَالَ لَكَ أَجْرَانِ قَالَ ‏"‏ نَعَمْ مَا مِنْ مُسْلِمٍ يُصِيبُهُ أَذًى مَرَضٌ فَمَا سِوَاهُ إِلاَّ حَطَّ اللَّهُ سَيِّئَاتِهِ كَمَا تَحُطُّ الشَّجَرَةُ وَرَقَهَا ‏"‏‏.‏
Reference : Sahih al-Bukhari 5667
In-book reference : Book 75, Hadith 27
USC-MSA web (English) reference : Vol. 7, Book 70, Hadith 571
  (deprecated numbering scheme)