"O you who believe! Do your duty to Allah and fear Him. Seek the means of approach to Him, and strive hard in His Cause as much as you can. So that you may be successful."
[Surat Al-Mā'idah, Ayah 35]
Shaykh Abdur-Rahman bin Naasir as-Sa'dee (رحمه الله) mentioned in his tafseer:
O mankind! We have created you from a male and a female, and made you into nations and tribes, that you may know one another. Verily, the most honorable of you with Allah is that (believer) who has At-Taqwa [i.e. one of the Muttaqûn (pious - see). Verily, Allah is All-Knowing, All-Aware.