Washing off semen

 188. ´Abdullah bin Shihab Al-Khaulani said: I stayed in the house of ´Aishah as a guest, and had a wet dream, so (in the morning) I dipped (my garment) in water. A maidservant of ´Aishah saw me and she informed her. ´Aishah sent me a message and said: ´´What made you do that with your garment?´´ I said that I saw in a dream what a sleeper sees. She said: ´´Did you find (any trace of the fluid) on your clothes?´´ I said: ´´No.´´ She said: ´´Had you find anything, you should have washed it. I used to scratch dry semen off the garment of the Messenger of Allah salla alayhi wa sallam with my nail.´´