Shu'bah al-Kufi narrates: I was with Abu Burdah bin Abi Musa, and he said: O my son! Shall I not narrate to you a hadith that my father (Sayyiduna Abu Musa al-Ash'ari, may Allah be pleased with him) narrated to me from the Prophet (peace and blessings be upon him)? The Prophet (peace and blessings be upon him) said: "Whoever frees a slave, Allah Almighty frees, in exchange for each limb of that slave, each limb of (the one who freed him) from Hell."
Ahmad and al-Tabarani recorded it, and he said: This narration is reported from Sayyiduna Abu Musa al-Ash'ari (may Allah be pleased with him) only with this chain; the narrators of Ahmad are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب العتق / 7254