It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him): Hasan bin Ali (may Allah be pleased with them both) picked up a date from the dates of charity and put it in his mouth. The Messenger of Allah (peace and blessings be upon him) said to him: "Do not take it, do not take it." So he spat it out. The Prophet (peace and blessings be upon him) said: "Do you not know that charity is not lawful for us?"
Hadith Referenceمسند اسحاق بن راهويه / كتاب الزكوٰة / 274
Hadith Takhrij«بخاري ، كتاب الزكاة ، باب ما يذكر فى الصدقة للنبي صلى الله عليه وسلم ، رقم : 1491 . مسلم ، كتاب الزكاة ، باب تحريم الزكاة على رسول الله صلى الله عليه وسلم صلى الله عليه واله وسلم ، رقم : 69 . مسند احمد : 409/2 . سنن دارمي ، رقم : 1642 .»