It is narrated from Sayyiduna Rafi' bin Khadij (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The earnings of the cupper are impure, the payment of a prostitute is impure, and the price of a dog is impure."
Hadith Referenceالمعجم الكبير للطبراني / باب الراء / 4243