Abu Dawud Book 1, Hadith Number 272.

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

Narated By One of the Wives of the Prophet : Ikrimah reported on the authority of one of the wives of the Prophet (PBUH) saying: When the Prophet (PBUH) wanted to do something (i.e. kissing, embracing) with (his) menstruating wife, he would put a garment on her private part.