'Abdullah ibn 'Umar reported that the Messenger of Allah, may Allah bless him and grant him peace, said, "When the slave advises his master and is assiduous in the worship of his Lord, he receives a double reward."  

أَنَّ رَسُولَ اللهِ ﷺ قَالَ إِنَّ الْعَبْدَ إِذَا نَصَحَ لِسَيِّدِهِ وَأَحْسَنَ عِبَادَةَ رَبِّهِ لَهُ أَجْرُهُ مَرَّتَيْنِ  

'Three have a double reward: one of the People of the Book who believes in his Prophet and then believes in Muhammad has two rewards. When a slave carries out the due of Allah and the due of his master, he has a double reward. And (the third is) a man who has a slavegirl with whom he has intercourse and teaches her well and instructs her well and then sets her free and marries her. He has two rewards.'"  

قَالَ رَجُلٌ لِعَامِرٍ الشَّعْبِيِّ يَا أَبَا عَمْرٍو إِنَّا نَتَحَدَّثُ عِنْدَنَا أَنَّ الرَّجُلَ إِذَا أَعْتَقَ أُمَّ وَلَدِهِ ثُمَّ تَزَوَّجَهَا كَانَ كَالرَّاكِبِ بَدَنَتَهُ فَقَالَ عَامِرٌ حَدَّثَنِي أَبُو بُرْدَةَ عَنْ أَبِيهِ قَالَ قَالَ لَهُمْ رَسُولُ اللهِ ﷺ ثَلاَثَةٌ لَهُمْ أَجْرَانِ رَجُلٌ مِنْ أَهْلِ الْكِتَابِ آمَنَ بِنَبِيِّهِ وَآمَنَ بِمُحَمَّدٍ ﷺ فَلَهُ أَجْرَانِ وَالْعَبْدُ الْمَمْلُوكُ إِذَا أَدَّى حَقَّ اللهِ وَحَقَّ مَوَالِيهِ وَرَجُلٌ كَانَتْ عِنْدَهُ أَمَةٌ يَطَأهَا فَأَدَّبَهَا فَأَحْسَنَ تَأْدِيبَهَا وَعَلَّمَهَا فَأَحْسَنَ تَعْلِيمَهَا ثُمَّ أَعْتَقَهَا فَتَزَوَّجَهَا فَلَهُ أَجْرَانِ قَالَ عَامِرٌ أَعْطَيْنَاكَهَا بِغَيْرِ شَيْءٍ وَقَدْ كَانَ يَرْكَبُ فِيمَا دُونَهَا إِلَى الْمَدِينَةِ  

Abu Musa reported that the Messenger of Allah, may Allah bless him and grant him peace, said, "The slave who is excellent in the worship of his Lord and fulfils the duties of obedience and counsel which he owes to his master, has two rewards."  

قَالَ رَسُولُ اللهِ ﷺ الْمَمْلُوكُ الَّذِي يُحْسِنُ عِبَادَةَ رَبِّهِ وَيُؤَدِّي إِلَى سَيِّدِهِ الَّذِي فُرِضَ الطَّاعَةُ وَالنَّصِيحَةُ لَهُ أَجْرَانِ  

Abu Burda reported from his father that the Messenger of Allah, may Allah bless him and grant him peace, said, "The slave has two rewards when he carries out Allah's due in worship (or he said that he is excellent in his worship) and the right of his owner who owns him."  

قَالَ رَسُولُ اللهِ ﷺ الْمَمْلُوكُ لَهُ أَجْرَانِ إِذَا أَدَّى حَقَّ اللهِ فِي عِبَادَتِهِ أَوْ قَالَ فِي حُسْنِ عِبَادَتِهِ وَحَقَّ مَلِيكِهِ الَّذِي يَمْلِكُهُ