Musnad Ahmad 33:926

Muhammad ibn Bakr narrated to us, Ibn Jurayj informed us, and Rawh narrated to us, Ibn Jurayj narrated to us, Abu al-Zubayr narrated to me, that he heard Jabir ibn Abdullah saying: "We participated with the Prophet, peace and blessings of Allah be upon him, in the Hajj and the Umrah, every seven [people] in a camel. So we slaughtered seventy camels on that day."