Musnad Abu Ya'la al-Mawsili 163:11

Abu Sa’id al-Ashajj narrated to us, Ibn Idris narrated to us, from Abu al-Jahhaf Dawud ibn Abi ‘Awf, from Muhammad ibn ‘Amr al-Hashimi, from Zaynab bint ‘Ali, from Fatimah bint Muhammad, she said: The Prophet, may Allah bless him and grant him peace, looked at ‘Ali and said: "This one is in Paradise. And indeed, among his Shi’ah (followers) are a people who know Islam, then they reject it. They have a nickname; they are called the Rafidah. Whoever meets them, let him kill them, for they are polytheists."