It is narrated from Sayyiduna ‘Irbad bin Sariyah (may Allah be pleased with him), he says: The Messenger of Allah (peace and blessings of Allah be upon him) gave us such an admonition that eyes wept and hearts trembled. We said: O Messenger of Allah! This seems like a farewell admonition, so what do you enjoin upon us? He (peace and blessings of Allah be upon him) said:“I have left you upon a white (and clear Shari‘ah), whose night is as bright as its day. Only he who is doomed will go astray from it. Whoever among you lives (after me) will see much difference, so hold fast to my Sunnah and the Sunnah of the rightly guided caliphs, and cling to it firmly. And obedience (to the caliph) will be obligatory upon you, even if he is an Abyssinian slave. Indeed, the believer is like a bridled camel, wherever he is led, he follows.”