Sahih Muslim Book 3, Hadith Number 628.

Chapter : The quantity of water that is desirable for a bath because of sexual intercourse, bathing of the male and female with one vessel in the same condition and washing of one of them with the left-over of the other.

Hafsa, daughter of ‘Abd al-Rahman b. Abu Bakr, reported that ‘Aisha narrated to her that she and the Apostle of Allah (may peace be upon him) took a bath from the same vessel which contained water equal to three Mudds or thereabout.