Abu Dawud Book 1, Hadith Number 280.

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

Narated By Fatimah daughter of Abu Hubaysh : Urwah ibn az-Zubayr said that Fatimah daughter of Abu Hubaysh narrated to him that she asked the Apostle of Allah (PBUH) and complained to him about the flowing of (her) blood. The Apostle of Allah (PBUH) said to her: That is only (due to) a vein: look, when your menstruation comes, do not pray; and when your menstruation ends, wash yourself and then offer prayer during the period from one menstruation to another.