He should spit on the left three times and then recite,

Avoodhubillahi minash shaithanir rajeem

أَعُوْذُ بِاللهِ مِنَ الشَّيْطَانِ الرَّجِيْمِ

Meaning:
I Seek refuge with Allah from the accursed Satan.
(Book: Bukhari 6995)