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]. (DE)
App reference (DE): Book 18, Hadith 18 (DE)
Arabic/English book reference (DE): Book 18, Hadith 1528 (DE)