Sahih Muslim
The Book on Salutations and Greetings (Kitab As-Salam)
Book Number: 026 / Hadith Number: 5440
'A'isha reported that when Allah's Messenger (may peace be upon him) fell ill, he recited over his body Mu'awwidhatan and blew over him and when his sickness was aggravated I used to recite over him and rub him with his band with the hope that it was more blessed.