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)