Musnad Ahmad 32:216

Yahya narrated to us, from Shu'bah, who said: Abdullah ibn Abdullah ibn Jabr narrated to me, saying: I heard Anas ibn Malik say: "The Messenger of Allah, may Allah bless him and grant him peace, and a woman from his wives would perform ghusl (ritual bath) from a single vessel. And he would perform ghusl with five makkuks (a measure of volume), and he would perform wudu (ablution) with one makkuk."