Sahih Bukhari Volume 3, Book 34, Hadith Number 414.

Narated By Hisham bin ‘Urwa : From his father who heard ‘Aisha saying, “The Holy Verse; ‘Whoever amongst the guardians is rich, he should take no wages (from the property of the orphans) but If he is poor, let him have for himself what is just and reasonable (according to his labors)’ (4.6) was revealed concerning the guardian of the orphans who looks after them and manages favorably their financial affairs; If the guardian Is poor, he could have from It what Is just and reasonable, (according to his labors).”