Mishkat al-Masabih 11 Business Transactions كتاب البيوع 135

وَعَنْ أَبِي أُمَامَةَ: أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «مَنِ احْتَكَرَ طَعَامًا أَرْبَعِينَ يَوْمًا ثمَّ تَصَدَّقَ بِهِ لَمْ يَكُنْ لَهُ كَفَّارَةً» . رَوَاهُ رزين

Abu Umama reported God’s Messenger as saying, “If anyone hoards grain for forty days and then gives it in sadaqa , that will not act as an atonement for him.” Razin transmitted it.