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
Sahih al-Bukhari 2546

Narrated Ibn `Umar:

Allah's Messenger (ﷺ) said, "If a slave is honest and faithful to his master and worships his Lord (Allah) in a perfect manner, he will get a double reward."

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ، عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ ـ رضى الله عنهما ـ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏ "‏ الْعَبْدُ إِذَا نَصَحَ سَيِّدَهُ وَأَحْسَنَ عِبَادَةَ رَبِّهِ كَانَ لَهُ أَجْرُهُ مَرَّتَيْنِ ‏"‏‏.‏
Reference : Sahih al-Bukhari 2546
In-book reference : Book 49, Hadith 29
USC-MSA web (English) reference : Vol. 3, Book 46, Hadith 722
  (deprecated numbering scheme)