Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) passed by a house in which there were twelve men, and he (peace and blessings be upon him) said: "In this house there is someone whose fitnah (trial) for my Ummah will be worse than the fitnah of the Dajjal."
Al-Bazzar recorded it; its chain contains a narrator, Muslim bin Kaysan, who is da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الخلافة / 9237