Sahih Muslim Book - 1, Hadith - 284

و حَدَّثَنِي يَحْيَى بْنُ أَيُّوبَ وَقُتَيْبَةُ وَابْنُ حُجْرٍ جَمِيعًا عَنْ إِسْمَاعِيلَ بْنِ جَعْفَرٍ قَالَ ابْنُ أَيُّوبَ حَدَّثَنَا إِسْمَاعِيلُ قَالَ أَخْبَرَنِي الْعَلَاءُ عَنْ أَبِيهِ عَنْ أَبِي هُرَيْرَةَ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مَرَّ عَلَى صُبْرَةِ طَعَامٍ فَأَدْخَلَ يَدَهُ فِيهَا فَنَالَتْ أَصَابِعُهُ بَلَلًا فَقَالَ مَا هَذَا يَا صَاحِبَ الطَّعَامِ قَالَ أَصَابَتْهُ السَّمَاءُ يَا رَسُولَ اللَّهِ قَالَ أَفَلَا جَعَلْتَهُ فَوْقَ الطَّعَامِ كَيْ يَرَاهُ النَّاسُ مَنْ غَشَّ فَلَيْسَ مِنِّي.

It was narrated from Abu Hurairah that the Messenger of Allah (s.a.w) passed by a pile of foodstuff; he put his hand (deep) in it and found that it had gotten wet. He said: 'What is this, O seller of the foodstuff?' He said: 'It got rained on, O Messenger of Allah.' He said: 'Why don't you put it on top of the food so that people can see it? Whoever deceives (people) does not belong to me."'