[Machine] Regarding Muawiya's words in the conversation that took place between him and Yazid during the allegiance, Muawiya said to me that the Messenger of Allah ﷺ said, "If there are two caliphs on earth, kill one of them."  

لِمُعَاوِيَةَ فِي الْكَلَامِ الَّذِي جَرَى بَيْنَهُمَا فِي بَيْعَةِ يَزِيدَ وَأَنْتَ يَا مُعَاوِيَةُ أَخْبَرَتْنِي أَنَّ رَسُولَ اللهِ ﷺ قَالَ «إِذَا كَانَ فِي الْأَرْضِ خَلِيفَتَانِ فَاقْتُلُوا أَحَدَهُمَا»