It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "At the end of time there will be a people who will be called the Rafidah; they will reject Islam and cast it out. So fight and kill them, for they are polytheists."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12941