‏الإمارة : Hadeeth No:4568 It has been narrated on the authority of Aba Sa'id al-Khudri that the Messenger of Allaah (sallAllaahu alayhi wa sallam) said: When oath of allegiance has been taken for two caliphs, kill the one for whom the oath was taken later....

‏الأشربة : Hadeeth No:5052 This hadith has been reported on the authority of Abu Mas'ud Ansari through another chain of transmitters....