Musnad Ahmad 33:980

Abu Qatan and Kathir ibn Hisham narrated to us, they said: Hisham narrated to us, from Abu al-Zubayr, from Jabir ibn Abdullah, "That the Messenger of Allah (peace and blessings of Allah be upon him) was cupped while he was in the state of Ihram due to a sprain that was in his hip - or his back."