Narrated by Aisha (may Allah be pleased with her), she said: I used to scrape semen from the garment of the Messenger of Allah (ﷺ), then he (ﷺ) would wear that same garment and pray.
Hadith Referenceمسند الإمام الشافعي / كتاب الطهارة / 25
Abdullah bin Abbas (may Allah be pleased with them both) regarding semen that gets on clothes, said: "Remove it with a piece of wood or grass, because it is like saliva or nasal discharge."
Hadith Referenceمسند الإمام الشافعي / كتاب الطهارة / 26
Hadith Takhrijصحيح موقوفاً: أخرجه ابن أبي شيبة (924) - والدارقطنی: 1/ 125.
Mus'ab bin Sa'd narrates that when semen would get on Sa'd bin Abi Waqqas's (may Allah be pleased with him) clothes, if it was wet, he would clean it, and if it was dry, he would rub the clothes, and then he would pray in them.
Hadith Referenceمسند الإمام الشافعي / كتاب الطهارة / 27
Hadith Takhrijصحيح فقد توبع شيخ الشافعي: أخرجه ابن أبي شيبة: 918، 919 - والبيهقي في السنن الكبرى: 2/ 418 وفي معرفة السنن والآثار له (1261).