Messenger of Allah ﷺ said, "He who has a slave-girl and educates and treats her nicely and then manumits and marries her, will get a double reward."  

قَالَ رَسُولُ اللَّهِ ﷺ مَنْ كَانَتْ لَهُ جَارِيَةٌ فَعَالَهَا فَأَحْسَنَ إِلَيْهَا ثُمَّ أَعْتَقَهَا وَتَزَوَّجَهَا كَانَ لَهُ أَجْرَانِ  

"The Messenger of Allah said: 'There are three who will be given a twofold reward: A man who has a slave woman whom he disciplines and disciplines her well, and teaches and teaches her well, then he manumits her and marries her; a slave who fulfills his duty toward Allah and toward his masters; and a believer from among the People of the Book.'"  

قَالَ رَسُولُ اللَّهِ ﷺ ثَلاَثَةٌ يُؤْتَوْنَ أَجْرَهُمْ مَرَّتَيْنِ رَجُلٌ كَانَتْ لَهُ أَمَةٌ فَأَدَّبَهَا فَأَحْسَنَ أَدَبَهَا وَعَلَّمَهَا فَأَحْسَنَ تَعْلِيمَهَا ثُمَّ أَعْتَقَهَا وَتَزَوَّجَهَا وَعَبْدٌ يُؤَدِّي حَقَّ اللَّهِ وَحَقَّ مَوَالِيهِ وَمُؤْمِنُ أَهْلِ الْكِتَابِ  

"The Messenger of Allah said: 'There are three who will be given a twofold reward: A man who has a slave woman whom he disciplines and disciplines her well, and teaches and teaches her well, then he manumits her and marries her; a slave who fulfills his duty toward Allah and toward his masters; and a believer from among the People of the Book.'" (Using translation from Nasāʾī 3344)  

قَالَ رَسُولُ اللهِ ﷺ ثَلَاثَةٌ يُؤْتَوْنَ أَجْرَهُمْ مَرَّتَيْنِ رَجُلٌ كَانَتْ لَهُ أَمَةٌ فَأَدَّبَهَا فَأَحْسَنَ أَدَبَهَا وَعَلَّمَهَا فَأَحْسَنَ تَعْلِيمَهَا ثُمَّ أَعْتَقَهَا وَتَزَوَّجَهَا وَعَبْدٌ يُؤَدِّي حَقَّ اللهِ وَحَقَّ مَوَالِيهِ وَمُؤْمِنُ أَهْلِ الْكِتَابِ