Sahih al-Bukhari, Hadith 2546 ⓘ
Narrated Ibn `Umar: Allah's Messenger 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 " .
also referenced under: Book 49, Hadith 30 (In-Book) & Volume 3, Book 46, Hadith 722 (USC-MSA)