1. A Person from the people of the scriptures who believed in his prophet (Jesus or Moses) and then believed in the Prophet (ﷺ) Muhammad (i .e. has embraced Islam).
2. A slave who discharges his duties to Allah and his master.
3. A master of a woman-slave who teaches her good manners and educates her in the best possible way (the religion) and manumits her and then marries her."
In-book : Book 3, Hadith 39
USC-MSA web (English) : Vol. 1, Book 3, Hadith 97 (deprecated)