Abdah bin Abi Lubabah (may Allah have mercy on him) narrates from Sayyiduna Ibn Mas'ud (may Allah be pleased with him) that he said: No man should blindly follow another in his religion, such that if he believes, the other believes, and if he disbelieves, he too disbelieves. If anyone wishes to follow, let him follow those who have died and leave the living, for they are not safe from trial (fitnah).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب آداب القاضي / 20349