Musnad Ahmad 8:41

Waki’ narrated to us, Hisham narrated to us, from his father, from Sa’d, that the Prophet, peace and blessings of Allah be upon him, entered upon him to visit him while he was ill. He said: "O Messenger of Allah, shall I bequeath all of my wealth?" He said: "No." He said: "Then half?" He said: "No." He said: "Then a third?" He said: "The third, and the third is large—or much."