A person acknowledging in a dream that he is someone's slave is acknowledging his enmity. If he confesses to sin and disobedience, he will attain might, honor and repentance. Confessing to killing a person indicates attaining office and leadership, or safety.
Dream meaning · al-Nabulsi
Confession (acknowledgment) إقرار الإنسان
Source: al-Nabulsi, Ta'tir al-Anam fi Ta'bir al-Manam, p. 21. English translation by iDreamBot. Quran verses: Quran.com, Saheeh International.