Sahih Muslim Book 3, Hadith Number 635.

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.

Anas said: The Apostle of Allah (may peace be upon him) performed ablution with one Mudd and took bath with a Sa’ up to five Mudds.