Musnad Ahmad 1018:10

Waki’ narrated to us, Sufyan narrated to us, from ‘Abd al-Rahman ibn ‘Abis, from ‘Abd al-Rahman ibn Abi Layla, from some of the companions of Muhammad, may Allah bless him and grant him peace, who said: "The Prophet, may Allah bless him and grant him peace, only forbade continuous fasting (wisal) and cupping for the fasting person out of consideration for his companions, and he did not declare them unlawful."