Despising a Muslim includes ridiculing or showing contempt for him. This is forbidden because it implies transgression against one’s Muslim brother. Rather one should respect and treat him with dignity because the believer is a brother to another believer, as the Prophet (ﷺ) said and affirmed in many narrations.
Abu Hurairah (رضي الله عنه) narrated that Allah's Messenger (ﷺ) said, “It is enough evil for a Muslim to look down upon his (Muslim) brother.” [Muslim]
Qur'an verse about despising on fellow Muslims
وَلَقَدْ عَلِمْتُمُ ٱلَّذِينَ ٱعْتَدَوْا۟ مِنكُمْ فِى ٱلسَّبْتِ فَقُلْنَا لَهُمْ كُونُوا۟ قِرَدَةً خَٰسِـِٔينَ
And well ye knew those amongst you who transgressed in the matter of the Sabbath: We said to them: "Be ye apes, despised and rejected."
Ibn Mas'ood (رضي الله عنه) narrated that Allah's Messenger (ﷺ) said: “The haughty (arrogant person), even with pride equal to a mustard seed in his heart, will not enter Paradise.”A man enquired, “What about a person who likes fine dress and fine shoes?”He (ﷺ) said,“Allah is Beautiful and loves beauty. Pride amounts to disclaiming (rejection) truth out of self esteem and despising people.” [Muslim]
All praise is due to Allah we ask Him to bless the Prophet Sallah Llah Alei Wasalam and the companions and let's die in the path of Qur'an and Sunnah.