Al-'Irbad bin Sariyah:
"One day after the morning Salat, the Messenger of Allah (ﷺ) exhorted us to the extent that the eyes wept and the hearts shuddered with fear. A man said: 'Indeed this is a farewell exhortation. [So what] do you order us O Messenger of Allah?' He said: 'I order you to have Taqwa of Allah, and to listen and obey, even in the case of an Ethiopian slave. Indeed, whomever among you lives, he will see much difference. Beware of the newly invented matters, for indeed they are astray. Whoever among you sees that, then he must stick to my Sunnah and the Sunnah of the rightly guided Khulafa', cling to it with the molars.'"