The Prophet ﷺ said: None of you must say: "My slave" (abdi) and "My slave-woman" (amati), and a slave must not say: "My lord" (rabbi or rabbati). The master (of a slave) should say: "My young man" (fataya) and "My young woman" (fatati), and a slave should say "My master" (sayyidi) and "My mistress" (sayyidati), for you are all (Allah's slave and the Lord is Allah, Most High. (Using translation from Abū Dāʾūd 4975)
قَالَ النَّبِيُّ ﷺ لَا يَقُولَنَّ أَحَدُكُمْ عَبْدِي وَأَمَتِي وَلَا يَقُولَنَّ الْمَمْلُوكُ رَبِّي وَرَبَّتِي لِيَقُلِ الْمَالِكُ فَتَايَ وَفَتَاتِي وَلْيَقُلِ الْمَمْلُوكُ سَيِّدِي وَسَيِّدَتِي فَإِنَّهُمُ الْمَمْلُوكُونَ وَالرَّبُّ اللهُ ﷻ