Musnad Ahmad 8:160

Husayn ibn Muhammad narrated to us, Jarir—meaning Ibn Hazim—narrated to us, from his uncle Jarir—meaning Ibn Zayd—from Amir ibn Sa’d ibn Abi Waqqas, from his father Sa’d, who said: I said, "O Messenger of Allah, shall I bequeath all of my wealth?" He said, "No." I said, "Then two-thirds of it?" He said, "No." I said, "Then half of it?" He said, "No." I said, "Then a third?" He said, "The third, and the third is large. That you leave your family wealthy is better for you than that you leave them dependent, begging from the hands of people."