When the freed slaves are from the people themselves, and charity is forbidden to them just as it is forbidden to the Prophet, peace and blessings be upon him—the obligatory charity, but not the voluntary charity.
The freed slave of the Prophet Muhammad (peace be upon him), Sayyiduna Abu Rafi’ (may Allah be pleased with him), narrates that the Messenger of Allah (peace be upon him) sent a man from Banu Makhzum to collect zakat, so he said to me, “Come with me.” I replied, “No, not until I go to the Messenger of Allah (peace be upon him) and seek permission from him.” He says that I went to the Prophet (peace be upon him) and asked him about this matter, so the Prophet (peace be upon him) said: “Indeed, zakat wealth is not lawful for us, and the freed slaves of a people are counted among that people.”
Hadith Referenceصحيح ابن خزيمه / جماع أبواب ذكر السعاية على الصدقة / 2344