From Sahih Bukhari (Hadith 5746):
Narrated `Aisha:Allah's Messenger (ﷺ) 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
Reference: Bukhari 5746