The Prophet ﷺ used to say to a sick person, while applying his saliva with his finger, "In the name of Allah, the dust of our land mixed with the saliva of one of us, that our sick may be healed by the permission of our Lord."
حدثنا أبو بكر بن أبي شيبة حدثنا سفيان عن عبد ربه عن عمرة
أن النبي ﷺ كان مما يقول للمريض ببزاقه بإصبعه بسم الله تربة أرضنا بريقة بعضنا ليشفى سقيمنا بإذن ربنا
Bukhari narrated it in "Medicine," chapter on the ruqyah of the Prophet ﷺ, hadith no. 5745, from the hadith of Sufyan through him, and Muslim narrated it in "Medicine," chapter on treating the sick with the last two surahs of the Quran and blowing, hadith no. 2194, from Ibn Abu Shayba through him.