Language:
كتاب فضائل القرآن
66
Virtues of the Qur'an
(14)
Chapter: The superiority of Al-Mu’awwidhat (Surat Al-Falaq and Surat An-Nas) (No.113 & 114)
(14)
‏باب فَضْلِ‏‏ الْمُعَوِّذَاتِ
Sahih al-Bukhari 5016

Narrated `Aisha:

Whenever Allah's Messenger (ﷺ) became sick, he would recite Mu'awwidhat (Surat Al-Falaq and Surat An- Nas) and then blow his breath over his body. When he became seriously ill, I used to recite (these two Suras) and rub his hands over his body hoping for its blessings.

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ، أَخْبَرَنَا مَالِكٌ، عَنِ ابْنِ شِهَابٍ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ، رضى الله عنها أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ إِذَا اشْتَكَى يَقْرَأُ عَلَى نَفْسِهِ بِالْمُعَوِّذَاتِ وَيَنْفُثُ، فَلَمَّا اشْتَدَّ وَجَعُهُ كُنْتُ أَقْرَأُ عَلَيْهِ وَأَمْسَحُ بِيَدِهِ رَجَاءَ بَرَكَتِهَا‏.‏
Reference : Sahih al-Bukhari 5016
In-book reference : Book 66, Hadith 38
USC-MSA web (English) reference : Vol. 6, Book 61, Hadith 535
  (deprecated numbering scheme)