From the Messenger of Allah ﷺ, and beware, he said, I heard the Messenger of Allah ﷺ say, "Whoever frees a Muslim man, it will be his ransom from the Fire, every bone of the freed man redeeming a corresponding bone of his own. And whoever frees two Muslim women, they will be his ransom from the Fire, every two of their bones redeeming one of his bones."
حدثنا أبو كريب حدثنا أبو معاوية عن الأعمش عن عمرو بن مرة عن سالم بن أبي الجعد عن شرحبيل بن السمط قال قلت لكعب يا
عن رسول الله ﷺ واحذر قال سمعت رسول الله ﷺ يقول من أعتق امرأ مسلما كان فكاكه من النار يجزئ كل عظم منه بكل عظم منه ومن أعتق امرأتين مسلمتين كانتا فكاكه من النار يجزئ بكل عظمين منهما عظم منه
Its chain of transmission is daif. Nasai narrated it in the Book of jihad, chapter on the reward of one who shoots an arrow in the path of Allah, mighty and sublime, no. 3146, from the hadith of Abu Muawiya, through this route. Abu Dawud also narrated it, no. 3967, through another route from Amr, through this route, and he said that Salim did not hear from Shurahbil. Part of the hadith has sahih corroborating narrations found in Muslim, no. 1509, and in Humaydi (no. 767, in my edition), and others besides them.