Ubaydullah bin Abdullah bin Utbah narrates from an Ansari man that he brought a black slave woman and said: O Messenger of Allah! It is obligatory upon me to free a believing slave. If you consider her a believer, I will set her free. The Prophet (peace be upon him) asked her: Do you testify that there is no god but Allah? She said: Yes! He asked: Do you testify that I am the Messenger of Allah? She said: Yes! The Prophet (peace be upon him) asked: Do you believe in life after death? She said: Yes! The Prophet (peace be upon him) said: Set her free.