‘Abdallah b. ‘Umar told that he heard God's Messenger say, “He who throws off obedience will meet God on the day of resurrection without possessing any plea, and he who dies without having taken an oath of allegiance will die like a pagan.”
Wa’il b. Hujr told that Salama b. Yazid al-Ju‘fi questioned God’s Messenger saying, “Prophet of God, tell us what you command us to do if commanders arise over us who demand of us what is due to them and refuse us what is due to us.” He replied, “Listen and obey, for they are responsible only for what has been laid on them (cf. Al-Qur’an, 24:54) and you for what has been laid on you.”
Abu Huraira reported the Prophet as saying, “The B. Isra’il were governed by the prophets, as often as one died another taking his place. There will be no prophet after me, but there will be numerous caliphs.” He was asked what command he had to give and replied, “Fulfil the oath of allegiance to each and give them their due for God will question them about what He asked them to guard.”
‘Abdallah b. Mas'ud told that God’s Messenger said to them, “After my death you will see appropriating the best things for themselves and other matters which you will disapprove.” He was asked what he commanded them to do and replied, “Give them what is due to them and ask God for what is due to you.”