It is narrated from Sayyiduna Ali (may Allah be pleased with him): I used to have a great deal of pre-seminal fluid (madhy), and I felt shy to ask the Messenger of Allah (peace and blessings be upon him) about it because of his daughter. So I told Miqdad bin al-Aswad (may Allah be pleased with him) to ask him (peace and blessings be upon him). He (peace and blessings be upon him) said: "He should wash his private part and perform ablution."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 560