Musnad Ahmad 167:3

Ahmad ibn Abd al-Malik narrated to us, Hammad ibn Zayd narrated to us, from Ali ibn Jud'an, from al-Hasan, from al-Dahhak ibn Sufyan al-Kilabi, that the Messenger of Allah (peace and blessings of Allah be upon him) said to him: "O Dahhak, what is your food?" He said: "O Messenger of Allah, meat and milk." He said: "Then what does it become?" He said: "To what you already know." He said: "For indeed, Allah, Blessed and Exalted is He, has made what comes out of the son of Adam a parable for the worldly life."