Sayyiduna Salamah bin al-Akwa' (may Allah be pleased with him) relates: "When we saw a man cursing his brother, we would consider that he had committed one of the major sins."
No one narrated this hadith from Sayyiduna Salamah (may Allah be pleased with him) except Yazid (may Allah have mercy on him), and no one from Yazid (may Allah have mercy on him) except Bukayr (may Allah have mercy on him), and Amr bin al-Harith (may Allah have mercy on him) is alone in narrating it.
Hadith Referenceالمعجم الأوسط / باب الميم / 6674
Hadith Gradingمحدثین:إسناده جيد
Hadith Takhrij«قال الهيثمي: إسناد الأوسط جيد «مجمع الزوائد ومنبع الفوائد، ج 8، ص 73»»