do not insult one another

يَا أَيُّهَا الَّذِينَ آمَنُوا لَا يَسْخَرْ قَوْمٌ مِّن قَوْمٍ عَسَىٰ أَن يَكُونُوا خَيْرًا مِّنْهُمْ وَلَا نِسَاءٌ مِّن نِّسَاءٍ عَسَىٰ أَن يَكُنَّ خَيْرًا مِّنْهُنَّ وَلَا تَلْمِزُوا أَنفُسَكُمْ وَلَا تَنَابَزُوا بِالْأَلْقَابِ بِئْسَ الِاسْمُ الْفُسُوقُ بَعْدَ الْإِيمَانِ وَمَن لَّمْ يَتُبْ فَأُولَٰئِكَ هُمُ الظَّالِمُونَ

سورة الحجرات الاية 11

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. Evil is the return to wickedness after having attained faith. Whoever does not repent — these are the wrongdoers. ―Quran 49:11

Islam counsels us to follow a better path when people insult us by not responding to them in the same manner, but rather to respond to their evil with good. Gentleness and forbearance are the general rules we need to follow in most situations.