I used to wash the traces of seminal fluid from the garment of the Messenger of Allah ﷺ, and he would go out to prayer with the water spots still visible on his garment.
أخبرنا سويد بن نصر قال أنبأنا عبد الله عن عمرو بن ميمون الجزري عن سليمان بن يسار
كنت أغسل الجنابة من ثوب رسول الله ﷺ فيخرج إلى الصلاة وإن بقع الماء لفي ثوبه
Bukhari narrated it in the Book of Wudu, chapter on washing semen and rubbing it out and washing what touches [the garment] from a woman, hadith no. 229, and Muslim in the Book of Purification, chapter on the ruling on semen, hadith no. 289, from the hadith of Abdullah bin Mubarak, transmitted through him. It is also in Al-Kubra, hadith no. 288.