She used to wash semen from the garment of the Messenger of Allah ﷺ, and he would go out to pray while I could still see the spots on his garment from where it had been washed.
حدثنا يزيد قال أخبرنا عمرو بن ميمون قال حدثنا سليمان بن يسار قال
أنها كانت تغسل المني من ثوب رسول الله ﷺ فيخرج فيصلي وأنا أنظر إلى البقع في ثوبه من أثر الغسل
Its isnad is sahih. Amr bin Maymun is al-Jazari, and he is trustworthy, his hadith being found in the collections of the group of six. The hadith has already appeared at 24089.