Messenger of Allah 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."  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ الْعَبْدُ إِذَا نَصَحَ سَيِّدَهُ وَأَحْسَنَ عِبَادَةَ رَبِّهِ كَانَ لَهُ أَجْرُهُ مَرَّتَيْنِ  

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."  

عَنْ أَبِي مُوسَى الأَشْعَرِيِّ ؓ قَالَ النَّبِيُّ ﷺ أَيُّمَا رَجُلٍ كَانَتْ لَهُ جَارِيَةٌ فَأَدَّبَهَا فَأَحْسَنَ تَأْدِيبَهَا وَأَعْتَقَهَا وَتَزَوَّجَهَا فَلَهُ أَجْرَانِ وَأَيُّمَا عَبْدٍ أَدَّى حَقَّ اللَّهِ وَحَقَّ مَوَالِيهِ فَلَهُ أَجْرَانِ  

Messenger of Allah ﷺ said, "A pious slave gets a double reward." Abu Huraira added: By Him in Whose Hands my soul is but for Jihad (i.e. holy battles), Hajj, and my duty to serve my mother, I would have loved to die as a slave.  

قَالَ رَسُولُ اللَّهِ ﷺ لِلْعَبْدِ الْمَمْلُوكِ الصَّالِحِ أَجْرَانِ وَالَّذِي نَفْسِي بِيَدِهِ لَوْلاَ الْجِهَادُ فِي سَبِيلِ اللَّهِ وَالْحَجُّ وَبِرُّ أُمِّي لأَحْبَبْتُ أَنْ أَمُوتَ وَأَنَا مَمْلُوكٌ  

The Prophet ﷺ said, "Goodness and comfort are for him who worships his Lord in a perfect manner and serves his master sincerely."  

قَالَ النَّبِيُّ ﷺ نِعْمَ مَا لأَحَدِهِمْ يُحْسِنُ عِبَادَةَ رَبِّهِ وَيَنْصَحُ لِسَيِّدِهِ