Musannaf Ibn Abi Shaybah

Hazrat Ali (may Allah be pleased with him) says that a lot of madhy (pre-seminal fluid) would come out from me. Since the daughter of the Messenger of Allah was in my marriage, I felt shy to ask (the Prophet), so I told a man and he asked the Prophet on my behalf. The Prophet (peace and blessings be upon him) said: When you see madhy, perform ablution and clean your private part, and if you see semen, then perform ghusl (full ritual bath).