The Messenger of Allah ﷺ said, "The Muslim is the brother of the Muslim. He does not betray him, lie to him, or forsake him. Everything of a Muslim is inviolable to another Muslim, his honor, his wealth, and his blood. Piety is here. It is enough evil for a person to despise his Muslim brother."
حدثنا عبيد بن أسباط بن محمد القرشي حدثني أبي عن هشام بن سعد عن زيد بن أسلم عن أبي صالح
قال رسول الله ﷺ المسلم أخو المسلم لا يخونه ولا يكذبه ولا يخذله كل المسلم على المسلم حرام عرضه وماله ودمه التقوى ها هنا بحسب امرئ من الشر أن يحتقر أخاه المسلم
[Its chain of transmission is hasan]. Abu Dawud narrated it in the Book of Manners, chapter on backbiting, no. 4882, from the hadith of Asbat bin Muhammad, through the same route. It has a corroborating narration in Muslim's Sahih, no. 2564, so the hadith is sahih. On this subject, there is also a report from Ali [2736] and Abu Ayub [to come at 1932, and Bukhari in Adab al-Mufrad, no. 922].