كتاب المقدمات
The Book of Miscellany
(27)
Chapter: Reverence towards the Sanctity of the Muslims
(27)
- باب تعظيم حرمات المسلمين وبيان حقوقهم والشفقة عليهم ورحمتهم
Riyad as-Salihin 234
Abu Hurairah (May Allah bepleased with him) reported:
Messenger of Allah (ﷺ) said, "A Muslim is a brother to a Muslim. He should neither deceive him nor lie to him, nor leave him without assistance. Everything belonging to a Muslim is inviolable for a Muslim; his honour, his blood and property. Piety is here (and he pointed out to his chest thrice). It is enough for a Muslim to commit evil by despising his Muslim brother."

[At- Tirmidhi, who categorized it as Hadith Hasan].

وعن أبي هريرة رضي الله عنه قال‏:‏ قال رسول الله صلى الله عليه وسلم‏:‏ “المسلم أخو المسلم لا يخونه ولا يكذبه ولا يخذله، كل المسلم على المسلم حرام عرضه وماله ودمه، التقوى ههنا، بحسب امرئ من الشر أن يحقر أخاه المسلم” ‏(‏‏(‏رواه الترمذي وقال ‏:‏حديث حسن‏)‏‏)‏‏.‏
Reference : Riyad as-Salihin 234
In-book reference : Introduction, Hadith 234