The first Shia Imam, Ali ibn Abitaleb (AS) said:

Extinguish the flames of bigotry and hatred from the age of ignorance which are hidden in your hearts. Because this inappropriate arrogance and bigotry among Muslims originates from, induction of doubt and selfishness, corruption and Satan’s provocations [1].

[1] Nahjul Balaghah, Sermon 192.

Source:en.shafaqna.com