Sunan Ibn Majah, Hadith 222 ⓘ
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.'"
حَدَّثَنَا هِشَامُ بْنُ عَمَّارٍ، حَدَّثَنَا الْوَلِيدُ بْنُ مُسْلِمٍ، حَدَّثَنَا رَوْحُ بْنُ جَنَاحٍ أَبُو سَعْدٍ، عَنْ مُجَاهِدٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " فَقِيهٌ وَاحِدٌ أَشَدُّ عَلَى الشَّيْطَانِ مِنْ أَلْفِ عَابِدٍ " .
also referenced under: Book 1, Hadith 227 (In-Book) & Volume 1, Book 1, Hadith 222 (DarusSalam)