Sayyiduna Rabi'ah bin al-Harith and Sayyiduna Abbas bin Abd al-Muttalib (may Allah be pleased with them both) said: If we were to send these two young men (that is, the narrator Abd al-Muttalib bin Rabi'ah and al-Fadl) to the Messenger of Allah (peace and blessings be upon him), and the Messenger of Allah (peace and blessings be upon him) were to appoint them over this charity, they would deliver what people deliver and would receive the same benefit that other people receive. Then he narrated the full hadith up to the two of them coming to the Prophet (peace and blessings be upon him); then the Prophet (peace and blessings be upon him) said: "Beware! Charity is not permissible for Muhammad (peace and blessings be upon him) nor for the family of Muhammad; it is only the dirt of people." Then he narrated the full hadith about the marriage of the two of them and their dowry being paid from the khumus.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2859