The Messenger of Allah ﷺ said, "The worst of earnings are the fee paid to a prostitute, the price of a dog, and the earnings of a cupper."
أخبرنا شعيب بن يوسف عن يحيى عن محمد بن يوسف عن السائب بن يزيد
قال رسول الله ﷺ شر الكسب مهر البغي وثمن الكلب وكسب الحجام
Muslim narrated it in the Book of Musaqah, Chapter on the prohibition of the price of a dog and the earnings of a soothsayer, etc., hadith no. 1568, from the hadith of Yahya bin Saeed Qattan, with the same chain, and it is also in Sunan al-Kubra, hadith no. 4805.