Al-Hujurat 49:11

Ya ayyuha allatheena amanoola yaskhar qawmun min qawmin AAasa an yakoonookhayran minhum wala nisaon min nisa-in AAasaan yakunna khayran minhunna wala talmizoo anfusakum walatanabazoo bil-alqabi bi/sa al-ismualfusooqu baAAda al-eemani waman lam yatub faola-ikahumu aththalimoon

"O you who have believed, let not a people ridicule [another] people; perhaps they may be better than them; nor let women ridicule [other] women; perhaps they may be better than them. And do not insult one another and do not call each other by [offensive] nicknames. Wretched is the name [i.e., mention] of disobedience after [one's] faith. And whoever does not repent - then it is those who are the wrongdoers."

Al-Hujurat 49:11, translation by Sahih International