Sahih Bukhari Volume 4, Book 51, Hadith Number 26.
Narated By Ibn ‘Umar : In the lifetime of Allah’s Apostle , Umar gave in charity some of his property, a garden of date-palms called Thamgh. ‘Umar said, “O Allah’s Apostle! I have some property which I prize highly and I want to give it in charity.” The Prophet; said, “Give it in charity (i.e. as an endowment) with its land and trees on the condition that the land and trees will neither be sold nor given as a present, nor bequeathed, but the fruits are to be spent in charity.” So ‘Umar gave it in charity, and it was for Allah’s Cause, the emancipation of slaves, for the poor, for guests, for travelers, and for kinsmen. The person acting as its administrator could eat from it reasonably and fairly, and could let a friend of his eat from it provided he had no intention of becoming wealthy by its means.