Abu Hurairah reported the Messenger of Allah ﷺ as saying:
when two men abuse one another, what they say is laid to the charge of the one who began it, so long as the one who is wronged does not go over the score.

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ، حَدَّثَنَا عَبْدُ الْعَزِيزِ، - يَعْنِي ابْنَ مُحَمَّدٍ - عَنِ الْعَلاَءِ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ " الْمُسْتَبَّانِ مَا قَالاَ فَعَلَى الْبَادِي مِنْهُمَا مَا لَمْ يَعْتَدِ الْمَظْلُومُ " .