al-Laith bin Sa'd الليث بن سعد · The Book of al-Bay'ah

"I came to the Prophet and said to him: 'I pledge to you to hear and obey in what I like and what I dislike.' The Prophet said: 'Can you do that, O Jarir,' or, 'Are you able for that?' He said: Say: As much as I can.' So he accepted my pledge (for that), and that I be sincere toward every Muslim."

"I gave my pledge to the Prophet to hear and obey, and he told me to add the words.' In as much as you can, and to be since toward every Muslim"'. (Sahih) '

"The Messenger of Allah said: 'Whoever obeys me, obeys Allah, and whoever disobeys me, disobeys Allah. Whoever obeys my governor (Amir), he has obeyed me, and whoever disobeys my governor, he has disobeyed me."'

"The Imam is like a shield whose orders should be obeyed when they (the Muslims) fight, and where they should seek protection. If he enjoins fear of Allah and behaves justly, then he will be rewarded, but if he enjoins otherwise, then it will be a burden (of sin) on him."