The command to kill whoever divides the Ummah of Muhammad (peace and blessings be upon him)

It is narrated from Sayyiduna Arfajah bin Shurayh al-Aslami (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said (raising his hands): "Soon after me there will be many trials and disorders. So whomever you see wanting to divide the affair of the Ummah of Muhammad while they are united, kill him, whoever he may be among the people."
This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it. I have judged it to be on the condition of the two Shaykhs because Shu'bah bin al-Hajjaj, Sufyan bin Sa'id, Shayban bin Abd al-Rahman and Ma'mar bin Rashid narrated it from Ziyad bin Ilaqah; then I found that Abu Hazim al-Ashja'i, Amir al-Sha'bi, Abu Ya'fur al-Abdi and other narrators corroborated Ziyad bin Ilaqah in narrating it from Arfajah. All the narrations of this chapter are collected with me in a separate volume (juz'), so there is no further need to mention these narrations. Furthermore, Imam Muslim recorded the hadith of Abu Nadrah from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "When allegiance is given to two caliphs, kill the latter of the two." Its explanation is found in the hadith of Abd al-Rahman bin Abd Rabb al-Ka'bah from Abdullah bin Amr (may Allah be pleased with them both), which Imam Muslim recorded.

It is narrated from Sayyiduna Abu Dharr (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "O Abu Dharr, how will you be when death strikes the people so abundantly that a house (meaning a grave) will be obtained in exchange for a slave?" I said: Whatever Allah and His Messenger choose for me. Then he (peace and blessings be upon him) said: "How will you be when such severe hunger strikes the people that you will come to your mosque but, out of weakness, will not have the strength to return to your bed, and getting up from your bed to come to the mosque will become impossible for you?" I said: Whatever Allah and His Messenger consider best for me. He (peace and blessings be upon him) said: "Hold to chastity and self-restraint." Then he said: "How will you be when there is so much killing among the people that Hijarat al-Zayt (a place in Madinah) will be drowned in blood?" I said: Allah and His Messenger know best. He (peace and blessings be upon him) said: "Stay in your house." I said: O Messenger of Allah, should I not take up my sword and confront the one who does this? He (peace and blessings be upon him) said: "In that case you would become a partner of those people in their sin." I said: O Messenger of Allah, what if someone forces his way into my house? He (peace and blessings be upon him) said: "If you fear that the glint of the sword will overawe you, then do like this (he indicated): throw an edge of your cloak over your face, so that he bears the burden of his sins and yours and becomes one of the people of Hell."
This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it, because Hammad bin Zayd narrated it from Abu Imran al-Jawni, from al-Musha'ath bin Tarif, from Abdullah bin al-Samit.

It is narrated from Sayyiduna Abu Dharr (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said something similar (like the previous hadith).