Arabic text
عن أبي الدرداء رضي الله عنه عن النبي صلى الله عليه وسلم قال: «مَنْ رَدَّ عَنْ عِرْضِ أَخِيهِ رَدَّ اللهُ عَنْ وَجْهِهِ النَّارَ يَوْمَ الْقِيَامَةِ».
Translation
Abu ad-Dardā’ (may Allah be pleased with him) reported: The Prophet (may Allah’s peace and blessings be upon him) said: "Whoever protects the honor of his brother in his absence, Allah will protect his face from the Fire on the Day of Judgment."
Explanation
The Prophet (may Allah's peace and blessings be upon him) informs that if a Muslim defends the honour of his fellow Muslim in his absence by preventing others from backbiting him, Allah will protect him from the punishment on the Day of Judgment.
Source: HadeethEnc.com