Majma al-Zawaid — Hadith 4485

Abu al-Hawra narrates: We were with Sayyiduna Imam Hasan bin Ali (may Allah be pleased with him) when he was asked: "What do you remember about the Prophet (peace and blessings be upon him), or from the Prophet (peace and blessings be upon him)?" He said: Once I was walking along with the Prophet (peace and blessings be upon him), and he passed by a heap of charity dates. I took a date and put it in my mouth, and the Prophet (peace and blessings be upon him) took it out along with its saliva. One of those present said: "There would have been no harm if you had left it." The Prophet (peace and blessings be upon him) said: "Indeed we, that is, the family of Muhammad, charity is not lawful for us." Sayyiduna Imam Hasan (may Allah be pleased with him) said: I also remember the command of the five prayers from the Prophet (peace and blessings be upon him).
Ahmad, Abu Ya'la and al-Tabarani in al-Mu'jam al-Kabir recorded it, and the narrators of Ahmad are thiqat (trustworthy).