I advise you to fear Allah and to hear and obey, even if an Abyssinian slave. You will see after me great discord. So, hold fast to my Sunnah and the Sunnah of the rightly guided Caliphs

The Prophet (may Allah's peace and blessings be upon him) delivered an eloquent sermon that filled the Companions' hearts with fear and filled their eyes with tears. They said: O Messenger of Allah, it seems as if it is an admonition by one who will soon leave us - seeing his earnest effort in doing so. Hence, they asked him to give them advice that they would hold onto after him. He said: I advise you to fear Allah Almighty by carrying out duties and avoiding prohibitions. And to hear and obey, i.e., hear and obey the rulers, even if your ruler or the one who seized authority over you is a slave. In other words, if the most inferior among people became your ruler, you should not disdain to obey him, out of fear of turbulence and strife, for whoever lives from you after me will see a great discord. Then, he (may Allah's peace and blessings be upon him) clarified that the way out of this discord is by adhering firmly to his Sunnah and to the Sunnah of the rightly guided Caliphs after him, namely Abu Bakr as-Siddīq, ‘Umar ibn al-Khattāb, ‘Uthmān ibn ‘Affān, and ‘Ali ibn Abi Tālib (may Allah be pleased with them all), and by biting onto it with the molar teeth, i.e., by strictly observing and holding fast to the Sunnah. He (may Allah's peace and blessings be upon him) also warned them against the newly introduced matters in religion, as every religious innovation is a misguidance.