Musnad Ahmad 612:3

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from 'Amr ibn Murrah, from Salim ibn Abi al-Ja'd, from Shurahbil ibn al-Simt, who said: A man said to Ka'b ibn Murrah—or Murrah ibn Ka'b—: "Narrate to us a hadith that you heard from the Messenger of Allah, may Allah bless him and grant him peace—may your father be sacrificed for Allah—and be cautious." He said: I heard the Messenger of Allah, may Allah bless him and grant him peace, saying: "Any man who emancipates a Muslim man, it will be his ransom from the Fire; for every bone of his bones, a bone of his bones will be recompensed. And any Muslim man who emancipates two Muslim women, they will be his ransom from the Fire; for every two bones of their bones, a bone of his bones will be recompensed. And any Muslim woman who emancipates a Muslim woman, she will be her ransom from the Fire; for every bone of her bones, a bone of her bones will be recompensed."