Hold fast to my Sunnah and the Sunnah of the rightly guided caliphs

It is narrated from Sayyiduna al-Irbad bin Sariyah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) led us in the morning (Fajr) prayer, then turned his blessed face towards us and gave us such a moving admonition that hearts trembled and eyes shed tears. We said: O Messenger of Allah! It seems as though this is the admonition of one bidding farewell, so give us some counsel. He (peace and blessings be upon him) said: "I counsel you to fear Allah, and to listen and obey (the ruler), even if a slave is made your leader; for whoever of you lives (after me) will see much disagreement. So hold fast to my Sunnah and the Sunnah of the rightly guided caliphs (al-Khulafa' al-Rashidun); bite onto it with your molar teeth, and beware of newly invented matters (in the religion), for every innovation is misguidance."
This hadith is sahih (authentic) and there is no hidden defect ('illah) in it. Imam Bukhari used Abd al-Rahman bin Amr and Thawr bin Yazid as evidence, and mentioned this hadith at the beginning of his Book of Holding Fast to the Sunnah. In my view, both of them (Imams Bukhari and Muslim) were under the impression that no one besides Thawr bin Yazid narrated from Khalid bin Ma'dan, whereas Muhammad bin Ibrahim bin al-Harith, whose hadith is found in the two Sahihs, also narrated it from Khalid bin Ma'dan.

It is narrated from Sayyiduna al-Irbad bin Sariyah (may Allah be pleased with him), who was from Banu Sulaym and among the People of the Suffah, that one day the Messenger of Allah (peace and blessings be upon him) came out to us and admonished the people, encouraging them and also warning them (of an evil end). Then he (peace and blessings be upon him) said: "Worship Allah and do not associate anything with Him; obey the one whom Allah has put in charge of your affairs; and do not dispute authority with those who hold it, even if he is an Abyssinian slave. It is binding on you to hold to what you know of the Sunnah of your Prophet and the way of the rightly guided caliphs (al-Khulafa' al-Rashidun), and to hold firmly to this truth with your molar teeth."
This chain is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), and I know of no hidden defect ('illah) in it.

It is narrated from Sayyiduna al-Irbad bin Sariyah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) gave us such an admonition that eyes shed tears and hearts trembled. We said: O Messenger of Allah! This seems like the counsel of one bidding farewell; what do you enjoin upon us? He (peace and blessings be upon him) said: "I have left you upon a bright path (Islam) whose night is as (clear as) its day; no one will deviate from it after me except one who is destined to perish. Whoever of you lives will see much disagreement, so it is binding on you to follow what you know of my Sunnah and the way of the rightly guided caliphs (al-Khulafa' al-Rashidun) who come after me; and hold fast to obedience, even if it be to an Abyssinian slave. Hold onto it firmly with your molar teeth." Asad bin Wada'ah used to add in this hadith: "Indeed the believer is like a camel with a rope through its nose: wherever it is led, it goes."

Sayyiduna al-Irbad bin Sariyah (may Allah be pleased with him), about whom this verse was revealed: "Nor (is there any blame) on those who, when they came to you that you might provide them with mounts, and you said, 'I find nothing on which to mount you', turned back with their eyes overflowing with tears out of grief that they could not find the means to spend (in jihad)" [Surah al-Tawbah: 92], relates that one day the Messenger of Allah (peace and blessings be upon him) led us in the morning (Fajr) prayer and then gave us a most eloquent admonition, from which eyes shed tears and hearts quaked. Someone said: O Messenger of Allah! It seems as though this is the admonition of one bidding farewell; what do you counsel us? He (peace and blessings be upon him) said: "I counsel you to fear Allah, and to listen and obey (the ruler), even if he is an Abyssinian slave; for whoever of you lives will see intense disagreement. So adhere to my Sunnah and the way of the rightly guided caliphs (al-Khulafa' al-Rashidun); hold on to it firmly and bite onto it with your molar teeth. And beware of new matters in the religion, for every new thing is an innovation, and every innovation is misguidance."