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.'" (ES)
English reference (ES): Vol. 1, Book 1, Hadith 222 (ES)
Arabic reference (ES): Book 1, Hadith 227 (ES)