Abdullah bin al-Samit narrates from Sayyiduna Abu Dharr (may Allah be pleased with him) that he reached al-Rabadhah when the iqamah for the prayer had already been called, and a slave was leading them. It was said: "This is Abu Dharr (may Allah be pleased with him)." So he began to step back, and Abu Dharr (may Allah be pleased with him) said: "My dear friend (peace and blessings be upon him) advised me with three things: that I listen and obey, even if it is an Abyssinian slave with mutilated limbs."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5119
Mu'adh bin Mu'adh narrated it from Shu'bah, and in this hadith he said: A slave was leading them in prayer. They said to Abu Dharr (may Allah be pleased with him): "Go forward." He refused, so the slave went forward and led them in prayer. Then he mentioned the hadith.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5120
Ibn Abi Mulaykah (may Allah have mercy on him) says: We used to visit the Mother of the Believers Aishah (may Allah be pleased with her) at the upper part of the valley: myself, Ubayd bin Umayr, al-Miswar bin Makhramah (may Allah be pleased with him) and many people. Abu Amr, the slave of Aishah (may Allah be pleased with her), used to lead us in prayer. Abu Amr had not yet been freed at that time, and he was the imam of the family of Muhammad bin Abi Bakr and of Urwah.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5121
Hisham bin Urwah narrates from his father that Abu Amr Dhakwan was the slave of Sayyidah Aishah (may Allah be pleased with her), and she freed him. He used to lead her in the night prayer in Ramadan and lead her in prayer while he was a slave.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5122
Nafi' narrates from Ibn Umar (may Allah be pleased with them both) that when the first Muhajirun came, they stopped at al-Usbah before the arrival of the Prophet (peace and blessings be upon him), and Salim (may Allah be pleased with him), the freed slave of Abu Hudhayfah (may Allah be pleased with him), used to lead them in prayer; he knew the most Qur'an.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5123