It has been narrated on the authority of Anas b. Malik that it was said to the Prophet (ﷺ):

Would that you approached Abdullah b. Ubayy (to persuade him to accept Islam). The Prophet (ﷺ) (accordingly) went to him, riding a donkey, and (a party of) Muslims also went (with him). On the way they had to walk over a piece of land affected with salinity. When the Prophet (ﷺ) approached him, he said: Do not come near me. By Allah, the obnoxious smell of your donkey has offended me. (As a rejoinder to this remark), a man from the Ansar said: By God, the smell of the donkey of the Messenger of Allah (ﷺ) is better than your smell. (At this), a man from the tribe of 'Abdullah got furious. Then people from both sides got furious and exchanged blows with sticks, hands and shoes. (The narrator says) that (after this scuffle) we learnt that (the Qur'anic verse):" It two parties of the Believers have a quarrel, make ye peace between them" (xlix. 9) was revealed about these fighting parties.

حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ الأَعْلَى الْقَيْسِيُّ، حَدَّثَنَا الْمُعْتَمِرُ، عَنْ أَبِيهِ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ قِيلَ لِلنَّبِيِّ صلى الله عليه وسلم لَوْ أَتَيْتَ عَبْدَ اللَّهِ بْنَ أُبَىٍّ قَالَ فَانْطَلَقَ إِلَيْهِ وَرَكِبَ حِمَارًا وَانْطَلَقَ الْمُسْلِمُونَ وَهِيَ أَرْضٌ سَبِخَةٌ فَلَمَّا أَتَاهُ النَّبِيُّ صلى الله عليه وسلم قَالَ إِلَيْكَ عَنِّي فَوَاللَّهِ لَقَدْ آذَانِي نَتْنُ حِمَارِكَ ‏.‏ قَالَ فَقَالَ رَجُلٌ مِنَ الأَنْصَارِ وَاللَّهِ لَحِمَارُ رَسُولِ اللَّهِ صلى الله عليه وسلم أَطْيَبُ رِيحًا مِنْكَ - قَالَ - فَغَضِبَ لِعَبْدِ اللَّهِ رَجُلٌ مِنْ قَوْمِهِ - قَالَ - فَغَضِبَ لِكُلِّ وَاحِدٍ مِنْهُمَا أَصْحَابُهُ - قَالَ - فَكَانَ بَيْنَهُمْ ضَرْبٌ بِالْجَرِيدِ وَبِالأَيْدِي وَبِالنِّعَالِ - قَالَ - فَبَلَغَنَا أَنَّهَا نَزَلَتْ فِيهِمْ ‏{‏ وَإِنْ طَائِفَتَانِ مِنَ الْمُؤْمِنِينَ اقْتَتَلُوا فَأَصْلِحُوا بَيْنَهُمَا‏}‏ ‏.‏