Abu Dawud Book 1, Hadith Number 372.

Chapter : A peerson who is sexually defiled is permitted to eat anything before washing.

Narated By ‘Aisha : I used to rub off the semen from the clothe of the Apostle of Allah (PBUH). He then would pray in it.

Abu Dawud said: Mughairah, Abu Ma’shar and wasil also narrated it to the same effect.