Why did the Noble Messenger forbid referring to slaves as "abd" (slave), while the Holy Quran used it in more than one Surah, such as His Almighty saying: "And a believing slave" in Surat Al-Baqarah, and "from among your slaves" in Surat An-Nur?

The prohibition narrated from the Prophet, peace and blessings be upon him, in the Two Sahihs and other collections, against saying "my slave" (male and female) and "my servant" (male and female) and "my boy," is for the purpose of self-aggrandizement, not for description or identification. The reason for the prohibition is the fear of a person arrogantly, haughtily, and proudly attributing a slave to himself. This is negated if the attribution is to someone other than the speaker, or if there is no attribution at all.