From Sahih Bukhari (Hadith 6319):
Narrated `Aisha:Whenever Allah's Messenger (ﷺ) went to bed, he used to blow on his hands while reciting the Mu'auwidhat ( i.e. Suratal-Falaq 113 and Surat-an-Nas 114) and then pass his hands over his body
Reference: Bukhari 6319