None of you should say: My bondman, for all of you are the bondmen of Allah, but say: My young man, and the servant should not say: My Lord, but should say: My chief. (Using translation from Muslim 2249b)
قَالَ رَسُولُ اللهِ ﷺ لَا يَقُولَنَّ أَحَدُكُمْ عَبْدِي فَإنَّ كُلَّكُمْ عَبْدٌ وَلَكِنْ لِيَقُلْ فَتَايَ وَلَا يَقُلْ أَحَدُكُمْ مَوْلَايَ فَإِنَّ مَوْلَاكُمُ اللهُ وَلَكِنْ لِيَقُلْ سَيِّدِي