"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.'" (Using translation from Nasāʾī 3653)
يَا رَسُولَ اللهِ إِنَّ أُمِّي أَوْصَتْ أَنْ يُعْتَقَ عَنْهَا رَقَبَةٌ مُؤْمِنَةٌ وَعِنْدِي جَارِيَةٌ نُوبِيَّةٌ سَوْدَاءُ فَقَالَ ادْعُ بِهَا فَجَاءَ بِهَا فَقَالَ لَهَا النَّبِيُّ ﷺ مَنْ رَبُّكِ؟ قَالَتْ اللهُ قَالَ مَنْ أَنَا؟ قَالَتْ أَنْتَ رَسُولُ اللهِ قَالَ أَعْتِقْهَا فَإِنَّهَا مُؤْمِنَةٌ