Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) said: "Let none of you be an 'imma'ah'." People said: O Abu Abd al-Rahman, what is an imma'ah? He said: "The one who says: I am simply with the people; if they are guided, I will be guided, and if they go astray, I will go astray. Indeed, let each of you firmly resolve within himself that if people disbelieve, he will not disbelieve."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 8733