Sunnah.com reference : Book 7, Hadith 45English translation : Book 7, Hadith 819Arabic reference : Book 7, Hadith 816
Narrated Abu Hurairah (RA):
Allah's Messenger (ﷺ) once came upon a heap of grain, and when he put his hand inside it, his fingers felt some dampness. So, he asked, "What is this, O owner of the grain?" He replied, "Rain had fallen on it, O Allah's Messenger." He said, "Why did you not put it (the damp part) on the top of the foodstuff so that people might see it? Whoever cheats has nothing to do with me."

[Reported by Muslim].
وَعَنْ أَبِي هُرَيْرَةَ ‏- رضى الله عنه ‏- { أَنَّ رَسُولَ اَللَّهِ ‏- صلى الله عليه وسلم ‏-مَرَّ عَلَى صُبْرَةِ طَعَامٍ, فَأَدْخَلَ يَدَهُ فِيهَا, فَنَالَتْ أَصَابِعُهُ بَلَلًا , فَقَالَ: 
" مَا هَذَا يَا صَاحِبَ اَلطَّعَامِ? " قَالَ: أَصَابَتْهُ اَلسَّمَاءُ يَا رَسُولَ اَللَّهِ.‏ فَقَالَ: أَفَلَا جَعَلْتَهُ فَوْقَ اَلطَّعَامِ; كَيْ يَرَاهُ اَلنَّاسُ? مَنْ غَشَّ فَلَيْسَ مِنِّي }  رَوَاهُ مُسْلِمٌ  1‏ .‏‏1 ‏- صحيح.‏ رواه مسلم ( 102 )‏.‏ والصبرة: الكومة المجتمعة من الطعام.‏