Musnad Abu Ya'la al-Mawsili 109:109

Abdullah ibn Umar ibn Aban narrated to us, Abd al-Rahim ibn Sulayman narrated to us, from Yahya ibn Abi Unaysah and Ubaydullah ibn Umar, from Abu al-Zubayr, from Jabir: That the Messenger of Allah (may Allah bless him and grant him peace) threw the Jamrah with pebbles like the pebbles of al-khadhf (pebbles thrown by placing them between two fingers).