حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ الْقَعْنَبِيُّ، عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ إِنَّ الْعَبْدَ إِذَا نَصَحَ لِسَيِّدِهِ وَأَحْسَنَ عِبَادَةَ اللَّهِ فَلَهُ أَجْرُهُ مَرَّتَيْنِ ‏"‏ ‏.‏

‘Abd Allah b. ‘Umar reported the Messenger of Allah (May peace be upon him) as saying: when a slave acts sincerely towards his master and worship Allah well, he will have a double reward. Translation Not Available

Book Ref: Sunan Abi Dawud Book 43 Hadith 5169
Web Ref:  Sunan Abi Dawud Book 42 Hadith 5150