٣٢٦ - باب تحريم قوله لمسلم: يا كافر

From Ibn ʿUmar (may Allah be pleased with them both), who said: The Messenger of Allah (peace and blessings be upon him) said: «When a man says to his brother: O disbeliever, it has settled upon one of them; if he is as he said, otherwise it returns upon him.» Agreed upon (al-Bukhārī and Muslim).

From Abū Dharr (may Allah be pleased with him): that he heard the Messenger of Allah (peace and blessings be upon him) say: «Whoever calls a man a disbeliever, or says: enemy of Allah, when he is not so, it returns upon him.» Agreed upon (al-Bukhārī and Muslim). «It returns»: reverts.