“Almighty Allaah swt has said in the Holy Quran: The most honourable of you in the sight of Allaah swt is the most pious of you.[f51] [so the criterion of distinction is piety.] Also, in the traditions: ‘People are equal like the tooth of a comb.”
See bihr al-anwar: vol.78, p.251, tradition.# 108, chap.23.
The Shia and their beliefs, Pg.20
Sayed Mohammad Shirazi