Musnad Abu Ya'la al-Mawsili 109:327

Abu Sa'id al-Qawariri narrated to us, Abd al-Rahman ibn Mahdi narrated to us, Sufyan narrated to us, from Abu al-Zubayr, from Jabir, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The believer eats in one intestine, and the disbeliever eats in seven intestines."