كتاب المغازى
64
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
(83)
Chapter: The sickness of the Prophet (saws) and his death
(83)
بَابُ مَرَضِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَوَفَاتِهِ
وَقَوْلِ اللَّهِ تَعَالَى: {إِنَّكَ مَيِّتٌ وَإِنَّهُمْ مَيِّتُونَ ثُمَّ إِنَّكُمْ يَوْمَ الْقِيَامَةِ عِنْدَ رَبِّكُمْ تَخْتَصِمُونَ}.

Narrated Aisha:

Whenever Allah's Messenger (ﷺ) became ill, he used to recite the Muawidhatan (i.e. the last two surahs of the Qur'an) and blow his breath over himself (after their recitation ) and rubbed his hands over his body. So when he was afflicted with his fatal illness. I started reciting the Muawidhatan and blowing my breath over him as he used to do and then I rubbed the hand of the Prophet (ﷺ) over his body.

حَدَّثَنِي حِبَّانُ، أَخْبَرَنَا عَبْدُ اللَّهِ، أَخْبَرَنَا يُونُسُ، عَنِ ابْنِ شِهَابٍ، قَالَ أَخْبَرَنِي عُرْوَةُ، أَنَّ عَائِشَةَ ـ رضى الله عنها ـ أَخْبَرَتْهُ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ إِذَا اشْتَكَى نَفَثَ عَلَى نَفْسِهِ بِالْمُعَوِّذَاتِ وَمَسَحَ عَنْهُ بِيَدِهِ فَلَمَّا اشْتَكَى وَجَعَهُ الَّذِي تُوُفِّيَ فِيهِ طَفِقْتُ أَنْفِثُ عَلَى نَفْسِهِ بِالْمُعَوِّذَاتِ، الَّتِي كَانَ يَنْفِثُ، وَأَمْسَحُ بِيَدِ النَّبِيِّ صلى الله عليه وسلم عَنْهُ‏.‏
Reference : Sahih al-Bukhari 4439
In-book reference : Book 64, Hadith 460
USC-MSA web (English) reference : Vol. 5, Book 59, Hadith 723
  (deprecated numbering scheme)