Abud-Darda' (May Allah be pleased with him) said:
The Prophet (ﷺ) said, "He who defends the honour of his (Muslim) brother, Allah will secure his face against the Fire on the Day of Resurrection."[At-Tirmidhi]. (AR)
App reference (AR): Book 18, Hadith 18 (AR)
Arabic/English book reference (AR): Book 18, Hadith 1528 (AR)