Musnad Ahmad 789:24

Yazid ibn Harun narrated to us, Abu al-Ashhab informed us, from Abu al-Hakam al-Bannani, from Abu Barzah, from the Prophet, peace and blessings of Allah be upon him, who said: "Indeed, among what I fear for you are the desires of error in your bellies and your private parts, and the misguiding temptations of passion."