1415. Narrated ‘Aaisha (radhi Allaahu anha) :
Whenever Allaah’s Messenger (Sallallaahu Alaihi Wasallam) became sick, he would recite Mu’awwidhat (Soorat 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 Surah) and rub his hands over his body hoping for its blessings.
[Saheeh Al-Bukhaari, Hadeeth No. 535, Vol. 6]
Source : The Book Of As-Salaam (Greetings) : Chapter 20 – To perform Ruqya over a patient by reciting Al-Mu’awwidhat [Soorat Al-Falaq (113), and Soorat An-Nas (114) and blowing one’s breath and saliva over the patient while reciting these Verses. Al-Lulu Wal-Marjan,Compiled by : Fuwad Abdul-Baqi, Translated by : Dr. Muhammad Muhsin Khan