Messenger of Allah ﷺ said "Three persons will have a double reward: 1. A Person from the people of the scriptures who believed in his prophet (Jesus or Moses) and then believed in the Prophet ﷺ Muhammad (i .e. has embraced Islam). 2. A slave who discharges his duties to Allah and his master. 3. A master of a woman-slave who teaches her good manners and educates her in the best possible way (the religion) and manumits her and then marries her."  

رَسُولُ اللَّهِ ﷺ: «ثَلاَثَةٌ لَهُمْ أَجْرَانِ: (١) رَجُلٌ مِنْ أَهْلِ الْكِتَابِ آمَنَ بِنَبِيِّهِ وَآمَنَ بِمُحَمَّدٍ ﷺ، (٢) وَالْعَبْدُ الْمَمْلُوكُ إِذَا أَدَّى حَقَّ اللَّهِ وَحَقَّ مَوَالِيهِ، (٣) وَرَجُلٌ كَانَتْ عِنْدَهُ أَمَةٌ (يَطَؤُهَا) فَأَدَّبَهَا فَأَحْسَنَ تَأْدِيبَهَا وَعَلَّمَهَا فَأَحْسَنَ تَعْلِيمَهَا ثُمَّ أَعْتَقَهَا فَتَزَوَّجَهَا فَلَهُ أَجْرَانِ۔»