Musnad Ahmad 799:95

Yahya ibn Abi Bukayr narrated to us, Zuhayr ibn Mu'awiyah said: We were informed by 'Abd al-Malik ibn 'Umayr, Husayn ibn Abi al-Hurr narrated to us, from Samurah ibn Jundub, who said: I was with the Messenger of Allah, may Allah bless him and grant him peace, and he called for a cupper. He ordered him to perform cupping on him. He brought out cupping vessels of his made from horns and applied them to him. He then made an incision with the tip of a blade and poured the blood into a vessel he had with him. A man from Banu Fazarah entered upon him and said: "What is this, O Messenger of Allah? Why do you allow this person to cut your skin?" He said: So I heard the Prophet, may Allah bless him and grant him peace, say: "This is cupping." He said: "And what is cupping?" He said: "It is among the best of what people use for medical treatment."