Sayyiduna Ali (may Allah be pleased with him) said: I was a man who had a great deal of madhy, and the daughter of the Prophet (peace and blessings be upon him) was married to me, so I felt too shy to ask him (peace and blessings be upon him). I asked a man to ask, and he asked him (peace and blessings be upon him), and he (peace and blessings be upon him) said: "When you find this, wash your private part and perform ablution."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4129