وَحَدَّثَنِي مَالِكٌ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ حَرْمَلَةَ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، أَنَّهُ كَانَ يَقُولُ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ الشَّيْطَانُ يَهُمُّ بِالْوَاحِدِ وَالاِثْنَيْنِ فَإِذَا كَانُوا ثَلاَثَةً لَمْ يَهُمَّ بِهِمْ ‏"‏ ‏.‏

Malik related to me from Abd ar-Rahman ibn Harmala that Said ibnal-Musayyab heard the Messenger of Allah, may Allah bless him andgrant him peace, say, "Shaytan concerns himself with one and two. Whenthere are three, he does not concern himself with them." Translation Not Available

Book Ref: Muwatta Imam Malik Book 54 Hadith 1802
Web Ref:  Muwatta Imam Malik Book 54 Hadith 36