Musnad Ahmad 799:135

'Abd al-Samad narrated to us, Jarir ibn Hazim narrated to us, 'Abd al-Malik ibn 'Umayr narrated to us, from Husayn ibn Abi al-Hurr, from Samurah ibn Jundub, who said: I saw the Messenger of Allah, may Allah bless him and grant him peace, while he was being cupped with a horn, and he was making incisions with the tip of a knife. A man from Shamkh entered and said to him: "Why do you allow your back or your neck to be subjected to what I see being done to it?" He said: "This is cupping, and it is among the best of what you use for medical treatment."