Sayyiduna Jabir bin Abdullah and Sayyiduna Abu Talhah bin Sahl al-Ansari (may Allah be pleased with them both) say that the Prophet (peace and blessings be upon him) said: "Whoever disgraces a Muslim in a place where his honour and sanctity are diminished, Allah will also disgrace him in a place where he will need His help; and whoever helps his Muslim brother in a place where his honour is at stake, Allah will also help him in a place where he will need help."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16682