From Sahih Bukhari (Hadith 4439):
Narrated Aisha:Whenever Allah's Messenger (ﷺ) became ill, he used to recite the Muawidhatan (i.e. the last two surahs of the Qur'an) and blow his breath over himself (after their recitation ) and rubbed his hands over his body. So when he was afflicted with his fatal illness. I started reciting the Muawidhatan and blowing my breath over him as he used to do and then I rubbed the hand of the Prophet (ﷺ) over his body
Reference: Bukhari 4439