I heard the Prophet ﷺ say, "The worst of earnings are the prostitute's payment, the price of a dog, and the cupper's earnings."
سمعت النبي ﷺ يقول: شر الكسب مهر البغي، وثمن الكلب، وكسب الحجام.
Muslim narrated it in Musaqah (1568:40), from Muhammad bin Hatim, who reported, Yahya bin Saeed Qattan told us, from Muhammad bin Yusuf, I heard Saaib bin Yazid narrate from Rafi bin Khadij who said, and he mentioned it.He also narrated it (41) through another route, from Saaib bin Yazid, with the wording, "The price of a dog is foul, the earnings of a prostitute are foul, and the earnings of a cupper are foul."