Isma'il bin Bashir, the freed slave of Banu Maghalah, narrates: I heard Sayyiduna Jabir bin Abdullah and Sayyiduna Abu Talhah bin Sahl al-Ansari (may Allah be pleased with them both) saying that the Messenger of Allah (peace and blessings be upon him) said: "Any person who abandons a Muslim at a time when his honour is being attacked and his sanctity is being violated, Allah will abandon him at a time when he wants Allah's help. And any person who helps a Muslim at a time when his honour is being attacked and his sanctity is being violated, Allah will help him at a time when he wants Allah's help."
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 4718