Sayyiduna Ali (may Allah be pleased with him) said: I was a man who suffered from the flow of madhi (pre-seminal fluid), but I felt shy to ask the Messenger of Allah (peace and blessings be upon him) about it. So I instructed Miqdad bin Al-Aswad, and he asked him (the Prophet, peace be upon him) on my behalf. He (the Prophet) said: "Ablution (wudu) is obligatory because of it."