Musnad Ahmad 32:940

Yahya ibn Sa'id narrated to us, from Humayd, who said: Anas ibn Malik was asked about the earnings of a cupper. He said: The Messenger of Allah (peace and blessings of Allah be upon him) was cupped; Abu Taybah cupped him, so he ordered two sa's of barley for him. And he spoke to his masters to lighten his tax for him, and he said: "The best of what you treat yourselves with is cupping and sea incense (Qust al-Bahri)."