Sayyiduna Abu Bakrah (may Allah be pleased with him) narrates that he went out to the Prophet (peace and blessings be upon him) while the Prophet (peace and blessings be upon him) was besieging Ta'if. They were twenty-three slaves who came out to the Prophet (peace and blessings be upon him); the Prophet (peace and blessings be upon him) declared them free, and these are the people who are called "Utaqa'" (the freed ones).
Al-Tabarani recorded it, and its narrators are the narrators of the Sahih.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب العتق / 7270