Abu Dawud
Purification (Kitab Al-Taharah)
Book Number: 001 / Hadith Number: 218
Narated By Anas : One day the Apostle of Allah (may peace be upon him) had sexual intercourse with (all) his wives with a single bath.
Abu Dawud said: This tradition has been transmitted through another chain of narrators.
Abu Dawud said: The tradition narrated by Anas is more sound than this tradition.