It was narrated from ‘Aishah that the Prophet ﷺ used to blow when performing Ruqyah.  

أَنَّ النَّبِيَّ ﷺ كَانَ يَنْفِثُ فِي الرُّقْيَةِ  

“Whenever the Prophet ﷺ fell ill, he would recite the Mu’awwidhat and blow, and when his pain grew worse, I would recite over him and wipe his hand over him, hoping for its blessing.”  

أَنَّ النَّبِيَّ ﷺ كَانَ إِذَا اشْتَكَى يَقْرَأُ عَلَى نَفْسِهِ الْمُعَوِّذَاتِ وَيَنْفِثُ فَلَمَّا اشْتَدَّ وَجَعُهُ كُنْتُ أَقْرَأُ عَلَيْهِ وَأَمْسَحُ بِيَدِهِ رَجَاءَ بَرَكَتِهَا