Imam Ali bin al-Madini (may Allah have mercy on him) says: The narration of Sayyiduna Shaddad bin Aws (may Allah be pleased with him) from the Messenger of Allah (peace and blessings be upon him), that he (peace and blessings be upon him) saw a man having cupping done in Ramadan, was narrated by Asim al-Ahwal through Abu Qilabah; and Yahya bin Abi Kathir also narrated it through Abu Qilabah from Sayyiduna Thawban. I consider both of these hadiths to be nothing but authentic, for it is possible that Abu Qilabah heard this hadith from both of them (Shaddad and Thawban). As for the permission for a fasting person to have cupping done, Imam Bukhari has recorded it in his "al-Jami' al-Sahih".