Sayyiduna Ali (may Allah be pleased with him) narrates that I used to have a lot of madhi (pre-seminal fluid), but I felt shy to ask the Messenger of Allah (peace and blessings be upon him), because his daughter (Sayyidah Fatimah al-Zahra, may Allah be pleased with her) was married to me. So I told a man (Miqdad bin Aswad, may Allah be pleased with him). He asked the Prophet (peace and blessings be upon him), and he said: Wudu is necessary because of it.