Musnad Ahmad 1086:2

Ishaq ibn Isa narrated to us, Malik informed us, from al-Zuhri, from Ibn Muhayyisah, from his father, that he sought permission from the Messenger of Allah (peace and blessings of Allah be upon him) regarding the wages of a cupper. He forbade him from it. He did not cease asking him about it until he said to him: "Feed it to your camel used for drawing water, and feed it to your slaves."