Hadith 1574
Abu Hurairah (May Allah be pleased with him) said:
وعن أبي هريرة رضي الله عنه أن رسول الله صلى الله عليه وسلم قال: "بحسب امرئ من الشر أن يحقر المسلم" . ((رواه مسلم، وقد سبق قريبًا بطوله)).
The Messenger of Allah (ﷺ) said, "It is enough evil for a Muslim to look down upon his (Muslim) brother." [Muslim].
In plain words
It is wrong enough on its own to look down on a fellow Muslim. Holding others in contempt is itself a serious fault.
Reference : Riyad as-Salihin 1574 In-book reference : Book 17, Hadith 64