Sahih al-Bukhari 2777
Narrated Ibn `Umar:
When `Umar founded an endowment he stipulated that its administrator could eat from it and also 
feed his friend on the condition that he would not store anything for himself from it.
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا حَمَّادٌ، عَنْ أَيُّوبَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ ـ رضى الله عنهما ـ أَنَّ عُمَرَ، اشْتَرَطَ فِي وَقْفِهِ أَنْ يَأْكُلَ مَنْ وَلِيَهُ وَيُوكِلَ صَدِيقَهُ غَيْرَ مُتَمَوِّلٍ مَالاً‏.‏