Musnad Ahmad 5:101

Khalaf narrated to us, Abu Ja’far—meaning al-Razi—and Khalid—meaning al-Tahhan—narrated to us, from Yazid ibn Abi Ziyad, from ‘Abd al-Rahman ibn Abi Layla, from ‘Ali ibn Abi Talib, who said: I was a man who frequently produced *madhy* (pre-seminal fluid), so I asked the Messenger of Allah, peace and blessings of Allah be upon him. He said: "As for *maniy* (semen), it requires *ghusl* (full ritual washing), and as for *madhy*, it requires *wudu* (ablution)."