There will be disagreement and division in my Ummah

It is narrated from Sayyiduna Anas bin Malik and Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Soon there will be disagreement and division in my Ummah. A people will appear who will speak very well, but their deeds will be bad; they will recite the Qur'an, but it will not go beyond their throats; they will pass out of the religion as an arrow passes right through the game; they will not return (to the religion) until the arrow returns to its notch. They are the worst of all creation and created beings. Tuba (glad tidings) to the one who kills them and the one whom they kill. They will call to the Book of Allah, though they have no connection with the Book of Allah. Whoever fights them will be closer to Allah than they are." The Companions said: O Messenger of Allah, what is their sign? He (peace and blessings be upon him) said: "Shaving the head."
Qatadah did not hear this hadith from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him); rather, he heard it from Abu al-Mutawakkil al-Naji, from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him).

It is narrated from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Their example is that of a man who shoots an arrow at game, then searches for the arrow where it has fallen; he picks it up and looks at its fuq (notch) but sees no trace of fat or blood on it; then he looks at its feathers and finds no trace of fat or blood there either; then he looks at its nasl (arrowhead) and sees nothing there either. Just as not the slightest trace of fat or blood clung to that arrow, likewise these people will have no connection with Islam."

It is narrated from Habbah al-Urani; he said: Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) and I went to Sayyiduna Hudhayfah (may Allah be pleased with him) and said: O Abu Abdullah, tell us what you heard from the Messenger of Allah (peace and blessings be upon him) about the trials. Sayyiduna Hudhayfah (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Stay with the Book of Allah wherever it turns (that is, follow the Book of Allah)." We said: When the people disagree, with whom should we be? He said: "Look for the group in which Ibn Sumayyah is, and hold fast to it, for he will be with the Book of Allah." The narrator said: I asked: Who is Ibn Sumayyah? He said: Do you not know him? I said: Make it clear to me. He said: He is Ammar bin Yasir. I heard the Messenger of Allah (peace and blessings be upon him) say concerning Ammar: "O Abu al-Yaqzan, you will not die until the rebellious group, deviating from the path of truth, kills you."
This hadith has various routes with sahih (authentic) chains; the two Shaykhs (Bukhari and Muslim) recorded some of them, but they did not record it with this wording.

It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that he said to Ikrimah and to his son Ali: Go to Abu Sa'id and hear from him the hadith about the Khawarij. So they both went and found him tending one of his gardens. When he saw us, he took his cloak and sat with his knees drawn up (against his stomach). Then he began speaking to us until he mentioned the (building of the) mosque. He said: We were carrying one brick at a time (while building the mosque), whereas Ammar was carrying two bricks at a time. The Prophet (peace and blessings be upon him) saw him and began shaking the dust off his head, saying: "O Ammar, why do you not carry one brick at a time as your companions do?" He said: I seek the reward from Allah Almighty. The narrator said: He (peace and blessings be upon him) kept shaking the dust off him and saying: "Alas for Ammar! A rebellious group will kill him." The narrator said: And at that time Ammar was saying: 'A'udhu billahi min al-fitan' (I seek refuge in Allah from trials).
This hadith is sahih (authentic) on the condition of Bukhari, but the two Shaykhs (Bukhari and Muslim) did not record it with this context.

It is narrated from Shaddad bin Abdullah Abu Ammar: I saw Sayyiduna Abu Umamah al-Bahili (may Allah be pleased with him) standing by the heads of the Haruriyyah (Khawarij) at the gate of Damascus, and he was saying: "These are the dogs of Hell." He said this three times, and he said: "The best of the slain are those whom these people killed." The narrator said: Tears flowed from the eyes of Sayyiduna Abu Umamah. A man asked him: O Abu Umamah, this saying of yours that these are the dogs of Hell, is it something you heard from the Messenger of Allah (peace and blessings be upon him), or is it your own opinion? He said: How bold I would be (in attributing it to him) had I not heard it from the Messenger of Allah (peace and blessings be upon him) once, twice or three times (until he counted seven times). A man said to him: I saw that tears came from your eyes. He said: (I wept because) these people were believers at first, then they disbelieved after their belief. Then he recited this verse: "And do not be like those who became divided and differed after the clear proofs had come to them." [Surah Al Imran: 105]. He recited this verse twice concerning them (the Khawarij).

It is narrated from Shaddad bin Abdullah Abu Ammar: I heard Sayyiduna Abu Umamah (may Allah be pleased with him) while he stood by the heads of the Haruriyyah (Khawarij) at the gate of Hims or the gate of Damascus, saying: "These are the dogs of Hell, the dogs of Hell, the worst of the slain beneath the shade of the sky, and the best of the slain are those whom they killed." Then he narrated the whole report like the hadith of Abu Hudhayfah.
This hadith is sahih (authentic) on the condition of Muslim, but the two Shaykhs (Bukhari and Muslim) did not record it. Imam Muslim, in his Sahih, recorded through the narration of Ikrimah bin Ammar from Sayyiduna Abu Umamah this saying of the Prophet (peace and blessings be upon him): "Allah Almighty says: O son of Adam, if you spend what is surplus to your needs, it is better for you" (to the end of the hadith). We have explained this text because most of its routes rest on the narration of Abu Ghalib from Abu Umamah, and the two Shaykhs did not record it.