Sahih al-Bukhari 2576
Narrated Abu Huraira:
Whenever a meal was brought to Allah's Messenger (ﷺ), he would ask whether it was a gift or Sadaqa 
(something given in charity). If he was told that it was Sadaqa, he would tell his companions to eat it, 
but if it was a gift, he would hurry to share it with them.
حَدَّثَنَا إِبْرَاهِيمُ بْنُ الْمُنْذِرِ، حَدَّثَنَا مَعْنٌ، قَالَ حَدَّثَنِي إِبْرَاهِيمُ بْنُ طَهْمَانَ، عَنْ مُحَمَّدِ بْنِ زِيَادٍ، عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏
"‏إِذَا أُتِيَ بِطَعَامٍ سَأَلَ عَنْهُ أَهَدِيَّةٌ أَمْ صَدَقَةٌ فَإِنْ قِيلَ صَدَقَةٌ‏.‏ قَالَ لأَصْحَابِهِ كُلُوا‏.‏ وَلَمْ يَأْكُلْ، وَإِنْ قِيلَ هَدِيَّةٌ‏.‏ ضَرَبَ بِيَدِهِ صلى الله عليه وسلم فَأَكَلَ مَعَهُمْ ‏"‏‏.‏