It was suggested to the Prophet ﷺ, "Why not go and visit Abdullah bin Ubayy?"So he set out toward him, riding a donkey, and the Muslims went along with him, the ground being salty marshland. When the Prophet ﷺ reached him, Abdullah said, "Get away from me. By Allah, the stench of your donkey has offended me."A man from the Ansar replied, "By Allah, the donkey of the Messenger of Allah ﷺ smells better than you do."A man from Abdullah's people became angry on his behalf, and then the companions of each man became angry on behalf of their own. A scuffle broke out among them with palm branches, fists, and sandals.We were told that the following verse was revealed concerning them, "If two parties among the believers fall into fighting, then make peace between them" [Hujurat 49:9].
قيل للنبي ﷺ لو أتيت عبد الله بن أبي؟ قال: فانطلق إليه، وركب حمارا، وانطلق المسلمون، وهي أرض سبخة، فلما أتاه النبي ﷺ قال: إليك عني، فوالله لقد آذاني نتن حمارك، قال: فقال رجل من الأنصار: والله لحمار رسول الله ﷺ أطيب ريحا منك. قال: فغضب لعبد الله رجل من قومه قال: فغضب لكل واحد منهما أصحابه. قال: فكان بينهم ضرب بالجريد وبالأيدي وبالنعال. قال: فبلغنا أنها نزلت فيهم: {وإن طائفتان من المؤمنين اقتتلوا فأصلحوا بينهما}
Bukhari reported it in the chapter on reconciliation (2691), and Muslim in the chapter on jihad and expeditions (1799), both of them through the route of Mutamir, from his father, from Anas bin Malik, who said, then he related it. The wording given here is that of Muslim, and Bukhari's wording is similar.Regarding the saying of Allah, "And if two parties among the believers fight, then make peace between them" [Hujurat 49:9]. This verse and what follows it show that transgression does not remove the designation of faith, for Allah called them believing brothers even though they were transgressors, the transgressor being the one who breaks away from the just leader. Hasan bin Ali bin Abu Talib acted upon this, and he brought about reconciliation between two great factions of the Muslims, as is related in the sahih collections.