Sahih Muslim | Book 9 | Hadith Number 3603

Narrated by Abu Huraira (Allah be pleased with him)
Abu Huraira (Allah be pleased with him) reported Allah's Messenger (may peace be upon him) as saying: He who emancipates a slave, Allah will set free from Hell every limb (of his body) for every limb of his (slave's) body, even his private parts.