Sayyiduna al-Irbad bin Sariyah (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) gave us an admonition from which the eyes shed tears and the hearts became fearful. We said: "O Messenger of Allah, this is the admonition of one bidding farewell, so what covenant do you take from us?" He (peace and blessings be upon him) said: "I have left you upon a white (shining) path whose night is like its day; none will deviate from it after me except one who is destroyed. Whoever among you lives will see much disagreement. So hold fast to what you know of my Sunnah and the Sunnah of the rightly guided caliphs, and hold fast to obedience, even if he is an Abyssinian slave; bite onto it with your molar teeth. Indeed, the believer is like a camel with a ring in its nose: wherever it is led, it follows."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15710