Musnad Abu Ya'la al-Mawsili 110:32

Muhammad ibn Mansur al-Tusi narrated to us, Musa ibn Dawud narrated to us, Muhammad ibn Muslim narrated to us, from Amr ibn Dinar, from Abu al-Sha'tha', from Ibn Abbas, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Every division that was divided is according to what it was divided upon. And every division that Islam reached is according to what it was divided upon."