´It was narrated that Ash-Sharid bin Suwaid Ath-Thaqafi said:` "I came to the Messenger of Allah and said: 'My mother left a will saying that a slave should be freed on her behalf. I have a Nubian slave girl; will it suffice if I free her on her behalf?' He said: 'Bring her here.' The Prophet said to her: 'Who is your Lord?' She said: 'Allah.' He said: 'Who am I?' She said: 'The Messenger of Allah.' He said: 'Set her free , for she is a believer.'"
Explanation & Benefits
Hafiz Muhammad Ameen
(1) It is understood that freeing a believing slave is superior, and furthermore, the emancipation of a male slave and a female slave is equal in virtue.
(2) Whoever affirms the oneness of Allah (Tawhid) and the messengership of the Messenger of Allah (sallallahu alayhi wa sallam), his affirmation will be accepted, and no further proof will be demanded from him.
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 3683