Sayyiduna Anas (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "The freed slave of a people is one of them."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2867
(a) It is narrated from Abu Rafi' (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) sent a man from Banu Makhzum to collect charity, and he said to Abu Rafi' (may Allah be pleased with him): Come along with me; you too will get something from it. Abu Rafi' (may Allah be pleased with him) said: We will ask the Prophet (peace and blessings be upon him). So Abu Rafi' (may Allah be pleased with him) came to him (peace and blessings be upon him) and asked, and he (peace and blessings be upon him) said: "The freed slave of a people is one of them, and it is not permissible (lawful) for us to take charity."
(b) Since in this hadith he (peace and blessings be upon him) counted them (the freed slaves) like his family, as they are included with Banu Hashim and Banu al-Muttalib in the prohibition of charity, so likewise they will be included in the salah (blessings) too. And Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2868