Ibn Muhaisah Harithi (may Allah have mercy on him) says that his father sought permission from the Messenger of Allah (peace and blessings be upon him) to practice cupping, but the Messenger of Allah (peace and blessings be upon him) forbade him. He kept asking for permission repeatedly until the Messenger of Allah (peace and blessings be upon him) said: "Spend this earning on your camel and your slave."
Hadith Referenceالسنن المأثورة / باب في البيوع / 271