Abu al-Hawra' (may Allah have mercy on him) said: We were with Sayyiduna al-Hasan bin Ali (may Allah be pleased with him), and he was asked: "What do you remember from the Messenger of Allah (peace and blessings be upon him)?" He said: "I was walking with him (peace and blessings be upon him) one day, and he passed by a heap of the dates of charity. I found a date and put it into my mouth, and he (peace and blessings be upon him) took it out along with my saliva. Some of the people said: 'O Messenger of Allah, what harm would there have been had you left it?' He (peace and blessings be upon him) said: 'We, the family of Muhammad, charity is not lawful for us.'"
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2701