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].
Arabic/English book reference: Book 1, Hadith 234