Sahih al-Bukhari 2547
Sahih al-Bukhari · Book 49: Manumission of Slaves · A slave who worships his Lord and he is also honest and faithful to his master
Narrated Abu Musa Al-Ash`ari:
حَدَّثَنَا مُحَمَّدُ بْنُ كَثِيرٍ ، أَخْبَرَنَا سُفْيَانُ ، عَنْ صَالِحٍ ، عَنِ الشَّعْبِيِّ ، عَنْ أَبِي بُرْدَةَ ، عَنْ أَبِي مُوسَى الأَشْعَرِيِّ ـ رضى الله عنه ـ قَالَ النَّبِيُّ صلى الله عليه وسلم " أَيُّمَا رَجُلٍ كَانَتْ لَهُ جَارِيَةٌ فَأَدَّبَهَا فَأَحْسَنَ تَأْدِيبَهَا، وَأَعْتَقَهَا وَتَزَوَّجَهَا، فَلَهُ أَجْرَانِ، وَأَيُّمَا عَبْدٍ أَدَّى حَقَّ اللَّهِ وَحَقَّ مَوَالِيهِ، فَلَهُ أَجْرَانِ " .
The Prophet (ﷺ) said, "He who has a slave-girl and teaches her good manners and improves her education and then manumits and marries her, will get a double reward; and any slave who observes Allah's right and his master's right will get a double reward."