On the authority of Abū Najīh al-'Irbād ibn Sāriya (may Allah be pleased with him), who said:
The Messenger of Allah (may the blessings and peace of Allah be upon him) gave us a sermon by which our hearts were filled with fear and tears came to our eyes. We said: O Messenger of Allah, it is as though this is a farewell sermon, so counsel us. He said: I counsel you to fear Allah (may He be glorified) and to give absolute obedience even if a slave becomes your leader. Verily he among you who lives [long] will see great controversy, so you must keep to my Sunnah and to the Sunnah of the rightly-guided Rashidite Caliphs - cling to them stubbornly. Beware of newly invented matters, for every invented matter is an innovation and every innovation is a going astray and every going astray is in Hell-fire.
It was related by Abū Dāwūd and at-Tirmidhī, who said that it was a good and sound Hadith.
