Sayyiduna Abu Hurairah (may Allah be pleased with him) narrated from the Messenger of Allah (peace and blessings be upon him), he said: "I see a fallen date and pick it up with the intention of eating it, but then, fearing that it might be from charity, I throw it away."
Hadith Referenceمسند اسحاق بن راهويه / كتاب الزكوٰة / 287