He brought a black slave-girl and said, "Messenger of Allah, I am obligated to free a believing slave. If you consider this woman to be a believer, I will set her free."The Messenger of Allah ﷺ asked her, "Do you bear witness that there is no god but Allah?"She replied, "Yes."He asked, "Do you bear witness that I am the Messenger of Allah?"She replied, "Yes."He asked, "Do you believe in resurrection after death?"She replied, "Yes."He said, "Set her free."
حدثنا عبد الرزاق حدثنا معمر عن الزهري عن عبيد الله بن عبد الله
أنه جاء بأمة سوداء وقال يا رسول الله إن علي رقبة مؤمنة فإن كنت ترى هذه مؤمنة أعتقتها فقال لها رسول الله ﷺ أتشهدين أن لا إله إلا الله قالت نعم قال أتشهدين أني رسول الله قالت نعم قال أتؤمنين بالبعث بعد الموت قالت نعم قال أعتقها
Its isnad is sahih. Abdullah bin Abdullah is Ibn Harith bin Nawfal, and he is trustworthy according to everyone. Abu Dawud narrated the hadith from Abu Hurairah, that a man said, "I owe the freeing of a slave..." and he related the hadith, 3/231, no. 3284, in the book of Faith, chapter on the believing slave, and similarly Malik in Muwatta 2/77, in the book of Manumission, chapter on which slaves may be freed, and Ibn Abu Shayba 11/20, no. 10392, and Bayhaqi 7/388. Muslim narrated it from Muawiya bin Hakam, and likewise Nasai, and this has already come up shortly before among the hadiths of Muawiya bin Hakam.