Musnad Abu Ya'la al-Mawsili 3:159

Al-Qawariri narrated to us, Sufyan bin 'Uyaynah narrated to us, from 'Asim bin Kulayb, from Abu Burdah, from 'Ali, who said: The Messenger of Allah (ﷺ) forbade me from placing the ring on this or on this, meaning the index finger and the middle finger.