In the hadith, Aisha mentions:
It was narrated that ‘Aishah said: “I used to scrape the Janabah.”
On another occasion she said: “The semen from the garment of the Messenger of Allah.”
Sunan an-Nasa’i 296
There’s similar hadith, which I don’t care to repeat here. So who’s was the issue on Muhammad’s robe?
Narrated Abu Sa’eed:
Jami` at-Tirmidhi 3727
that the Messenger of Allah said to ‘Ali: “O ‘Ali! It is not permissible for anyone to be Junub in this Masjid except for you and I.”
Ali and his Junub is the cause of the Janabah on the robe of Muhammad that Aisha scrapes off.
Koran Contradiction 