narrated 'aisha (radi-allahu 'anha):

whenever the prophet (sallallahu 'alaihi wa sallam) went to bed every night, he used to cup his hands together and blow over it after reciting surat al-ikhlas, surat al-falaq and surat an-nas, and then rub his hands over whatever parts of his body he was able to rub, starting with his head,
face and front of his body. he used to do that three times.

bukhari vol. 6 : no. 536