'Irbad bin Sariyah (May Allah be pleased with him) reported:
One day Messenger of Allah (ﷺ) delivered us a very eloquent Khutbah on account of which eyes shed tears and hearts were full of tears. A man said: "O Prophet of Allah, this is as if it were a parting advice. So advise us". He (ﷺ) said, "I admonish you to fear Allah, to listen and obey even if an Abyssinian slave is appointed as your leader. Because whosoever among you shall live after me, will see much discord. So hold fast to my Sunnah and the examples of the Rightly- Guided Caliphs who will come after me. Adhere to them and hold to it fast. Beware of new things (in Deen) because every Bid'ah is a misguidance".[Abu Dawud and At- Tirmidhi].
Arabic/English book reference: Book 1, Hadith 157