Sayyiduna Irbad bin Sariyah (may Allah be pleased with him) says that the Messenger of Allah gave us a very effective sermon after the Fajr prayer, due to which eyes wept and hearts were filled with fear. One companion said: O Messenger of Allah! This seems like a farewell sermon, (so please give us some advice). The Prophet (peace and blessings be upon him) said: "I advise you to fear Allah, and to listen to and obey the leader, even if a Habashi (Abyssinian) slave is appointed over you. (Remember!) Whoever among you lives after me will see much disagreement, so hold fast to my Sunnah and the way of the rightly guided Caliphs, cling to it with your molar teeth. Beware of newly invented matters in religion, for every newly invented matter is an innovation, and every innovation is misguidance."