Language:
كتاب العتق
49
Manumission of Slaves
(16)
Chapter: A slave who worships his Lord and he is also honest and faithful to his master
(16)
باب الْعَبْدِ إِذَا أَحْسَنَ عِبَادَةَ رَبِّهِ وَنَصَحَ سَيِّدَهُ

Narrated Abu Musa Al-Ash`ari:

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."

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 ‏"‏‏.‏
Reference : Sahih al-Bukhari 2547
In-book reference : Book 49, Hadith 31
USC-MSA web (English) reference : Vol. 3, Book 46, Hadith 723
  (deprecated numbering scheme)