Sahih Muslim #4799 · The Book on Government

Sahih MuslimIt has been narrated on the authority of Aba Sa'id al-Khudri that the Messenger of Allah
Sahih Muslim · Book 33 · The Book on Government
Sahih Muslim · كتاب 33 · كتاب الإمارة
When oath of allegiance has been taken for two caliphs, kill the one for whom the oath was taken later.
وَحَدَّثَنِي وَهْبُ بْنُ بَقِيَّةَ الْوَاسِطِيُّ، حَدَّثَنَا خَالِدُ بْنُ عَبْدِ اللَّهِ، عَنِ الْجُرَيْرِيِّ، عَنْ أَبِي، نَضْرَةَ عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏
"‏ إِذَا بُويِعَ لِخَلِيفَتَيْنِ فَاقْتُلُوا الآخَرَ مِنْهُمَا ‏"‏ ‏.‏
Reference : Sahih Muslim 4799In-book reference : Book 33, Hadith 96