Musnad Ahmad 5:735

Abdullah narrated to us, Abu Khaythama narrated to me, Shababa ibn Sawwar narrated to us, Nu'aym ibn Hakim narrated to me, Abu Maryam narrated to me, Ali ibn Abi Talib narrated: That the Messenger of Allah, peace and blessings of Allah be upon him, said: "A people will pass out of Islam just as an arrow passes out of the game. They recite the Quran, but it does not go beyond their collarbones. Blessed is he who kills them and whom they kill. Their sign is a man with a deformed hand."