Abu Dawud Book 1, Hadith Number 357.

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

Narated By Mu’adhah : ‘Aisha was asked about (washing) the clothes of menstruating woman smeared with blood. She said: She should wash it; in case the mark is not removed she should change it by applying some yellow colour. I had three menstruations together while I lived with the Apostle of Allah (PBUH), but I did not wash my clothes.