It was narrated that Ibn 'Abbas said:
"The Messenger of Allah said: 'One Faqih (knowledgeable man) is more formidable against the Shaitan than one thousand devoted worshippers.'" (IT)
English reference (IT): Vol. 1, Book 1, Hadith 222 (IT)
Arabic reference (IT): Book 1, Hadith 227 (IT)