Abu Hurairah (May Allah be pleased with him) said:
The Messenger of Allah (ﷺ) said, "When two persons indulge in abusing each other, the beginner will be the sinner so long as the oppressed does not transgress the limits."[Muslim]. (RU)
App reference (RU): Book 18, Hadith 51 (RU)
Arabic/English book reference (RU): Book 18, Hadith 1561 (RU)