Sahih Bukhari Volume 7, Book 76, Hadith 5737

حَدَّثَنِي إِبْرَاهِيمُ بْنُ مُوسَى، أَخْبَرَنَا هِشَامٌ، عَنْ مَعْمَرٍ، عَنِ الزُّهْرِيِّ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ أَنَّ النَّبِيَّ صلى الله عليه وسلم كَانَ يَنْفُثُ عَلَى نَفْسِهِ فِي الْمَرَضِ الَّذِي مَاتَ فِيهِ بِالْمُعَوِّذَاتِ، فَلَمَّا ثَقُلَ كُنْتُ أَنْفِثُ عَلَيْهِ بِهِنَّ، وَأَمْسَحُ بِيَدِ نَفْسِهِ لِبَرَكَتِهَا‏.‏ فَسَأَلْتُ الزُّهْرِيَّ كَيْفَ يَنْفِثُ قَالَ كَانَ يَنْفِثُ عَلَى يَدَيْهِ، ثُمَّ يَمْسَحُ بِهِمَا وَجْهَهُ‏

Narrated By 'Aisha : During the Prophet's fatal illness, he used to recite the Mu'auwidhat (Surat An-Nas and Surat Al-Falaq) and then blow his breath over his body. When his illness was aggravated, I used to recite those two Suras and blow my breath over him and make him rub his body with his own hand for its blessings." (Ma'mar asked Az-Zuhri: How did the Prophet use to blow? Az-Zuhri said: He used to blow on his hands and then passed them over his face.)