The Prophet ﷺ was asked about the earnings of a cupper, and he said, "Feed it to your camel."
حدثنا سفيان بن عيينة عن أبي الزبير
أن النبي ﷺ سئل عن كسب الحجام فقال اعلفه ناضحك
Its isnad is sahih. It is found in Tirmidhi 3/575, no. 1277, in the Book of Sales, chapter on what has been said about the earnings of the cupper, where he said, hasan sahih, and in Ibn Majah 2166, in the Book of Trade, chapter on the earnings of the cupper.