Sahih Muslim Book 013, Hadith Number 3991.
Chapter : Will can be made only for one-third.
Amir b. Sa'd reported on the authority of his father (Sa'd b. Abi Waqqas): Allah's Messenger (may peace be upon him) visited me in my illness which brought me near death in the year of Hajjat-ul-Wada' (Farewell Pilgrimage). I said: Allah's Messenger, you can well see the pain with which I am afflicted and I am a man possessing wealth, and there is none to inherit me except only one daughter. Should I give two-thirds of my property as Sadaqa? He said: No. I said: Should I give half (of my property) as Sadaqa? He said: No. He (further) said: Give one-third (in charity) and that is quite enough. To leave your heirs rich is better than to leave them poor, begging from people; that you would never incur an expense seeking therewith the pleasure of Allah, but you would be rewarded therefore, even for a morsel of food that you put in the mouth of your wife. I said: Allah's Messenger, would I survive my companions? He (the Holy Prophet) said: If you survive them, then do such a deed by means of which you seek the pleasure of Allah, but you would increase in your status (in religion) and prestige; you may survive so that people would benefit from you, and others would be harmed by you, (The Holy Prophet) further said: Allah, complete for my Companions their migration, and not cause them to turn back upon their heels. Sa'd b. Khaula is, however, unfortunate. Allah's Messenger (may peace be upon him) felt grief for him as he had died in Mecca.