كتاب التفسير
65  
Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh))
(2)
"...But if he (the guardian) is poor, let him have for himself what is just and reasonable (according to his work). And when you release their property to them, take witness in their presence; and Allah is All-Sufficient in taking account." (V.4:6)
(2)
Sahih al-Bukhari 4575

Narrated Aisha:

regarding the Statement of Allah: "And whoever amongst the guardian is rich, he should take no wages, but if he is poor, let him have for himself what is just and reasonable (according to his work). This Verse was revealed regarding the orphan's property. If the guardian is poor, he can take from the property of the orphan, what is just and reasonable according to his work and the time he spends on managing it.

حَدَّثَنِي إِسْحَاقُ، أَخْبَرَنَا عَبْدُ اللَّهِ بْنُ نُمَيْرٍ، حَدَّثَنَا هِشَامٌ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ فِي قَوْلِهِ تَعَالَى ‏{‏وَمَنْ كَانَ غَنِيًّا فَلْيَسْتَعْفِفْ وَمَنْ كَانَ فَقِيرًا فَلْيَأْكُلْ بِالْمَعْرُوفِ‏}‏ أَنَّهَا نَزَلَتْ فِي مَالِ الْيَتِيمِ إِذَا كَانَ فَقِيرًا، أَنَّهُ يَأْكُلُ مِنْهُ مَكَانَ قِيَامِهِ عَلَيْهِ، بِمَعْرُوفٍ‏.‏
Reference : Sahih al-Bukhari 4575
In-book reference : Book 65, Hadith 97
USC-MSA web (English) reference : Vol. 6, Book 60, Hadith 99
  (deprecated numbering scheme)