Hadithcore
Sahih al-Bukhari, 2777
sahih

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.‏

References2 variants
In-Book Reference
Book 55, Hadith 40
USC-MSA web (English) reference
Vol. 4, Book 51, Hadith 38 (deprecated numbering scheme)