Musnad Ahmad 27:937

Hassan narrated to us, Abd al-Rahman ibn Abd Allah—meaning Ibn Dinar—narrated to us, from Zayd ibn Aslam, from Ibn Umar, from the Prophet, peace and blessings of Allah be upon him, who said: "Whoever withdraws a hand from obedience, there is no argument for him on the Day of Resurrection. And whoever dies while separating from the community, he has died a death of ignorance."