49:13 O mankind! We created you from a single (pair) of a male and a female and made you into nations and tribes that ye may know each other (not that ye may despise each other). Verily the most honored of you in the sight of Allah is (he who is) the most righteous of you. And Allah has full knowledge and is well acquainted (with all things).
If you speak of a person behind their back and that evil is not found in them then you are guilty of slander. (Abu Dawood & Tirmizi)