Musnad Ahmad 32:900

Aswad ibn Amir Shadhan narrated to us, Sharik narrated to us, from Abdullah ibn Isa, from Abdullah ibn Jabr, from Anas ibn Malik, who said: "The Prophet, peace and blessings of Allah be upon him, used to perform ablution (wudu) with a vessel containing two ratls, and he would perform ghusl with a sa'."