Musnad Ahmad 1101:22

I read to Abd al-Rahman: Malik, and Ishaq narrated to us, Malik informed us, from Abu al-Nadr, the freed slave of Umar ibn Ubayd Allah, from Sulayman ibn Yasar, from al-Miqdad ibn al-Aswad: That Ali ibn Abi Talib ordered him to ask the Messenger of Allah (may Allah bless him and grant him peace) about a man who, when he approaches his wife, has *madhy* (pre-seminal fluid) discharge from him: what is upon him? Ali said: "For I have the daughter of the Messenger of Allah (may Allah bless him and grant him peace), and I am too shy to ask him." Al-Miqdad said: So I asked the Messenger of Allah about that, and he said: "If one of you finds that, let him sprinkle water on his private part, and let him perform his ablution for prayer."