The verse was revealed concerning the guardian of an orphan when he is poor, that he may eat from the orphan's wealth in a reasonable manner in return for his care of him.
في قوله تعالى: ومن كان غنيا فليستعفف ومن كان فقيرا فلياكل بالمعروف
أنها نزلت في والي اليتيم إذا كان فقيرا: أنه يأكل منه مكان قيامه عليه بمعروف.
Bukhari related it in the tafsir (4575), and Muslim in the tafsir (3019), both through the route of Abdullah bin Numayr, who said, "Hisham narrated to us, from his father, from Ayesha," and he mentioned it. The wording given here is Bukhari's, for Muslim did not present his own wording with this chain, but instead referred back to the hadith preceding it.