Whoever protects the honor of his brother in his absence, Allah will protect his face from the Fire on the Day of Judgment. [At-Tirmidhi]
"«مَنْ رَدَّ عَنْ عِرْضِ أَخِيهِ رَدَّ اللَّهُ عَنْ وَجْهِهِ النَّارَ يَوْمَ الْقِيَامَةِ». [صحيح.] - [رواه الترمذي وأحمد.]"