Musnad Ahmad 33:483

Harun ibn Ma'ruf narrated to us, Ibn Wahb narrated to us, 'Amr informed me that Bukayr narrated to him, that 'Asim ibn 'Umar ibn Qatadah narrated to him, that Jabir ibn 'Abdullah visited al-Muqanna', and said: "I will not depart until you are cupped, for I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'Indeed, in it is the cure.'"