It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them) that he said: Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) sent Sayyiduna Miqdad bin Aswad (may Allah be pleased with him) to the Messenger of Allah (peace and blessings of Allah be upon him) (to ask about an issue). So he asked the Messenger of Allah (peace and blessings of Allah be upon him): What should a person do if madhiy (pre-seminal fluid) comes out? The Messenger of Allah (peace and blessings of Allah be upon him) said: "Perform wudu and wash your private part."
Related hadith on this topic