A hadith I heard from the Messenger of Allah ﷺ. He said, I heard the Messenger of Allah ﷺ say, "Whoever frees a believing slave, it will be his ransom from the Fire."
حدثنا عبد الوهاب بن نجدة حدثنا بقية حدثنا صفوان بن عمرو حدثني سليم بن عامر عن شرحبيل بن السمط أنه قال
حديثا سمعته من رسول الله ﷺ قال سمعت رسول الله ﷺ يقول من أعتق رقبة مؤمنة كانت فداءه من النار
Graded hasan. Nasai narrated it in the chapter on jihad, "The Reward for Shooting an Arrow in the Cause of Allah, Mighty and Sublime," hadith 3144, from the hadith of Baqiyyah with this chain. The hadith has many corroborating narrations, and it was also narrated by Hurayz bin Uthman from Salim bin Amir with this chain, in Ahmad, 4/386.