Mukhtasar Bukhari (Abridged) 172 — Washing or rubbing off semen are

Umm al-Mu'mineen Aisha Siddiqa (may Allah be pleased with her) says: I used to wash the traces of janabah (semen stains) from the garment of the Prophet (peace and blessings of Allah be upon him). Then the Prophet (peace and blessings of Allah be upon him) would go out for prayer wearing the same garment, even though there would be water spots on his garment.