Narrated Yazid bin Abi Ubaid: I saw the trace of a wound in Salama's leg. I said to him, "O Abu Muslim! What is this wound?" He said, "This was inflicted on me on the day of Khaibar and the people said, 'Salama has been wounded.' Then I went to the Prophet and he puffed his saliva in it (i.e. the wound) thrice., and since then I have not had any pain in it till this hour."
Hadith Referenceصحيح البخاري / كتاب المغازي / 4206
Hadith Gradingمحدثین:أحاديث صحيح البخاريّ كلّها صحيحة
Hadith Commentary: ➊ This is the fourteenth hadith of Sahih al-Bukhari. Between Imam al-Bukhari rahimahullah and the Messenger of Allah sallallahu alayhi wa sallam, there are only three narrators. This means that Salamah ibn al-Akwa‘ radi Allahu anhu lived a very long life. ➋ In this hadith, Imam al-Bukhari’s rahimahullah teacher, Makki ibn Ibrahim, is a Tabi‘ al-Tabi‘i (follower of the followers), and Makki is his name, not a nisbah (attribution) to Makkah. ➌ The difference between (nafath), (nafakh), and (tafal) is that (nafakh) means blowing without saliva, whereas (tafal) contains saliva, and (nafath) is between (nafakh) and (tafal), meaning that it is a blow with a slight amount of saliva.
Source: Hidayat al-Qari: Commentary on Sahih Bukhari, Urdu, Page: 4206