Whenever the Messenger of Allah ﷺ was presented with food, he asked about it, If he was told that it was a gift, he ate out of that, and if he was told that it was a sadaqa he did not eat out of that.  

أَنَّ النَّبِيَّ ﷺ كَانَ إِذَا أُتِيَ بِطَعَامٍ سَأَلَ عَنْهُ فَإِنْ قِيلَ هَدِيَّةٌ أَكَلَ مِنْهَا وَإِنْ قِيلَ صَدَقَةٌ لَمْ يَأْكُلْ مِنْهَا