It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "I went back to my family and found a date lying on my bed. I picked it up and wanted to eat it, but then the thought came to me that it might be from charity, so I threw it away."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الصدقات / 13233