Sunan An-Nasa'i
Hadith #2612
It was narrated from Ihn Abi Rafi, from his father, that:the Messenger of Allah appointed a man from Banu Makhzum to collect Sadaqah. Abu Rafi wanted to go with him, but the Messenger of Allah said: ""The Sadaqah is not permissible for us, and the freed slave of a people is one of them