Language:
كتاب البيوع
34  
Sales and Trade
(95)
Chapter: Where there is no fixed judgement, the traditions and conventions of community are to be referred
(95)
بَابُ مَنْ أَجْرَى أَمْرَ الأَمْصَارِ عَلَى مَا يَتَعَارَفُونَ بَيْنَهُمْ فِي الْبُيُوعِ وَالإِجَارَةِ وَالْمِكْيَالِ، وَالْوَزْنِ، وَسُنَنِهِمْ عَلَى نِيَّاتِهِمْ وَمَذَاهِبِهِمِ الْمَشْهُورَةِ
Sahih al-Bukhari 2212

Narrated 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).

حَدَّثَنِي إِسْحَاقُ، حَدَّثَنَا ابْنُ نُمَيْرٍ، أَخْبَرَنَا هِشَامٌ، وَحَدَّثَنِي مُحَمَّدٌ، قَالَ سَمِعْتُ عُثْمَانَ بْنَ فَرْقَدٍ، قَالَ سَمِعْتُ هِشَامَ بْنَ عُرْوَةَ، يُحَدِّثُ عَنْ أَبِيهِ، أَنَّهُ سَمِعَ عَائِشَةَ ـ رضى الله عنها ـ تَقُولُ ‏{‏وَمَنْ كَانَ غَنِيًّا فَلْيَسْتَعْفِفْ وَمَنْ كَانَ فَقِيرًا فَلْيَأْكُلْ بِالْمَعْرُوفِ‏}‏ أُنْزِلَتْ فِي وَالِي الْيَتِيمِ الَّذِي يُقِيمُ عَلَيْهِ، وَيُصْلِحُ فِي مَالِهِ، إِنْ كَانَ فَقِيرًا أَكَلَ مِنْهُ بِالْمَعْرُوفِ‏.‏
Reference : Sahih al-Bukhari 2212
In-book reference : Book 34, Hadith 158
USC-MSA web (English) reference : Vol. 3, Book 34, Hadith 414
  (deprecated numbering scheme)