Sahih al-Bukhari 231
Narrated `Amr bin Maimun:
I heard Sulaiman bin Yasar talking about the clothes soiled with semen. He said that `Aisha had said, 
"I used to wash it off the clothes of Allah's Messenger (ﷺ) and he would go for the prayers while water spots 
were still visible on them.
حَدَّثَنَا مُوسَى، قَالَ حَدَّثَنَا عَبْدُ الْوَاحِدِ، قَالَ حَدَّثَنَا عَمْرُو بْنُ مَيْمُونٍ، قَالَ سَأَلْتُ سُلَيْمَانَ بْنَ يَسَارٍ فِي الثَّوْبِ تُصِيبُهُ الْجَنَابَةُ قَالَ قَالَتْ عَائِشَةُ كُنْتُ أَغْسِلُهُ مِنْ ثَوْبِ رَسُولِ اللَّهِ صلى الله عليه وسلم، ثُمَّ يَخْرُجُ إِلَى الصَّلاَةِ وَأَثَرُ الْغَسْلِ فِيهِ بُقَعُ الْمَاءِ‏.‏