Malik related to me from Ibn Shihab from Ibn Muhayyisa al-Ansari,one of the Banu Haritha, that he asked permission from the Messengerof Allah, may Allah bless him and grant him peace, to give payment forcupping, and he forbade him to do it. He continued to ask and seek hispermission until he said, "Feed the ones who drive your water-carryingcamels," meaning "your slaves."
USC-MSA web (English) reference: Book 54, Hadith 28
Arabic reference: Book 54, Hadith 1793