It is narrated from Sayyidah Umm Kulthum bint Ali (may Allah be pleased with her) - Ata bin al-Sa'ib (may Allah have mercy on him) said: I had come to her with some charity that had been ordered - and she said: Keep our young men away (from it), for Maymun or Mihran (may Allah be pleased with him), the freed slave of the Prophet (peace and blessings be upon him), told me that he passed by the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) said: "O Maymun - or Mihran - taking charity has been made unlawful for us, the Ahl al-Bayt, and our freed slaves are counted among us, so do not eat charity."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17961