Sahih al-Bukhari, Volume 7, Book 71, Hadith 642 (USC-MSA) ⓘ
Narrated `Aisha: Allah's Messenger used to read in his Ruqya, "In the Name of Allah" The earth of our land and the saliva of some of us cure our patient with the permission of our Lord." with a slight shower of saliva) while treating with a Ruqya.
حَدَّثَنِي صَدَقَةُ بْنُ الْفَضْلِ، أَخْبَرَنَا ابْنُ عُيَيْنَةَ، عَنْ عَبْدِ رَبِّهِ بْنِ سَعِيدٍ، عَنْ عَمْرَةَ، عَنْ عَائِشَةَ، قَالَتْ كَانَ النَّبِيُّ صلى الله عليه وسلم يَقُولُ فِي الرُّقْيَةِ " تُرْبَةُ أَرْضِنَا، وَرِيقَةُ بَعْضِنَا، يُشْفَى سَقِيمُنَا، بِإِذْنِ رَبِّنَا " .
also referenced under: Book 76, Hadith 61 (In-Book) & Hadith 5746 (DarusSalam)