It is good for a slave that he worships Allah well, and serves his master (well). It is good for him.  

عَنْ رَسُولِ اللَّهِ ﷺ فَذَكَرَ أَحَادِيثَ مِنْهَا وَقَالَ قَالَ رَسُولُ اللَّهِ ﷺ نِعِمَّا لِلْمَمْلُوكِ أَنْ يُتَوَفَّى يُحْسِنُ عِبَادَةَ اللَّهِ وَصَحَابَةَ سَيِّدِهِ نِعِمَّا لَهُ  

[Machine] The Messenger of Allah ﷺ said: "What a blessing it is for a servant that Allah will take his soul while he is in a state of worshiping his Lord and obeying his master. What a blessing it is for him."  

قَالَ رَسُولُ اللهِ ﷺ نِعِمَّا لِلْعَبْدِ أَنْ يَتَوَفَّاهُ اللهُ بِحُسْنِ عِبَادَةِ رَبِّهِ وَبِطَاعَةِ سَيِّدِهِ نِعِمَّا لَهُ وَنِعِمَّا لَهُ  

[Machine] And the Messenger of Allah, ﷺ , said: "What a great blessing for a slave to be taken while in the good worship of Allah and the company of His Prophet, what a great blessing for him."  

وَقَالَ رَسُولُ اللهِ ﷺ نِعْمَّا لِلْمَمْلُوكِ أَنْ يُتَوَفَّى بِحُسْنِعِبَادَةِ اللهِ وَصَحَابَةِ سَيِّدِهِ نِعِمَّا لَهُ