Sayyiduna Rafi‘ bin Khadij (may Allah be pleased with him) narrates: The Prophet (peace and blessings of Allah be upon him) said:“The earnings of the cupper are impure, the earnings of a prostitute are impure, and the price of a dog is impure.”
(Imam Ibn Hibban, may Allah have mercy on him, says:) The earnings of the cupper were declared unlawful when they are based on a specific condition, that is, when he says: I will extract this much blood for this much compensation. When this condition, which is implicit in the statement, is known, then this earning will be permissible because the Prophet (peace and blessings of Allah be upon him) himself permitted it for Sayyiduna Abu Taybah (may Allah be pleased with him). The Prophet (peace and blessings of Allah be upon him) permitted it through his action. As for the price of a dog and the earnings of a prostitute, both are unlawful.