Sunan Ibn Majah Book 0, Hadith 42

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ أَحْمَدَ بْنِ بَشِيرِ بْنِ ذَكْوَانَ الدِّمَشْقِيُّ، حَدَّثَنَا الْوَلِيدُ بْنُ مُسْلِمٍ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ الْعَلاَءِ، - يَعْنِي ابْنَ زَبْرٍ - حَدَّثَنِي يَحْيَى بْنُ أَبِي الْمُطَاعِ، قَالَ سَمِعْتُ الْعِرْبَاضَ بْنَ سَارِيَةَ، يَقُولُ قَامَ فِينَا رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ ذَاتَ يَوْمٍ فَوَعَظَنَا مَوْعِظَةً بَلِيغَةً وَجِلَتْ مِنْهَا الْقُلُوبُ وَذَرَفَتْ مِنْهَا الْعُيُونُ فَقِيلَ يَا رَسُولَ اللَّهِ وَعَظْتَنَا مَوْعِظَةَ مُوَدِّعٍ فَاعْهَدْ إِلَيْنَا بِعَهْدٍ فَقَالَ ‏ "‏ عَلَيْكُمْ بِتَقْوَى اللَّهِ وَالسَّمْعِ وَالطَّاعَةِ وَإِنْ عَبْدًا حَبَشِيًّا وَسَتَرَوْنَ مِنْ بَعْدِي اخْتِلاَفًا شَدِيدًا فَعَلَيْكُمْ بِسُنَّتِي وَسُنَّةِ الْخُلَفَاءِ الرَّاشِدِينَ الْمَهْدِيِّينَ عَضُّوا عَلَيْهَا بِالنَّوَاجِذِ وَإِيَّاكُمْ وَالأُمُورَ الْمُحْدَثَاتِ فَإِنَّ كُلَّ بِدْعَةٍ ضَلاَلَةٌ ‏"‏ ‏.‏

Yahya bin Abu Muta' said:I heard 'Irbad bin Sariyah say: 'One day, the Messenger of Allah (ﷺ) stood up among us and delivered a deeply moving speech to us that melted our hearts and caused our eyes to overflow with tears. It was said to him: 'O Messenger of Allah, you have delivered a speech of farewell, so enjoin something upon us.' He said: 'I urge you to fear Allah, and to listen and obey, even if (your leader) is an Abyssinian slave. After I am gone, you will see great conflict. I urge you to adhere to my Sunnah and the path of the Rightly-Guided Caliphs, and cling stubbornly to it. And beware of newly-invented matters, for every innovation is a going astray