Musnad Ahmad 949:13

Isma'il ibn Ibrahim narrated to us, Abu Rayhanah narrated to us, from Safinah, the companion of the Messenger of Allah, may Allah bless him and grant him peace, who said: "The Messenger of Allah, may Allah bless him and grant him peace, used to perform ghusl (full ablution) with a sa' (a measure), and he used to perform wudu (ablution) with a mudd (a measure)."