The Holy book Qur'an and the Sunnah: teachings of Prophet Muhammed (PBUH).
<< O’ mankind! We created you from a single pair of a male and a female, and made you into nations and tribes that you may know each other, not that you 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.>>