I relate the traditions of Allah's Messenger (ﷺ) to you for I would rather fall from the sky than attribute something to him falsely. But when I tell you a thing which is between you and me, then no doubt, war is guile. I heard Allah's Messenger (ﷺ) saying, "In the last days of this world there will appear some young foolish people who will use (in their claim) the best speech of all people (i.e. the Quran) and they will abandon Islam as an arrow going through the game. Their belief will not go beyond their throats (i.e. they will have practically no belief), so wherever you meet them, kill them, for he who kills them shall get a reward on the Day of Resurrection."
Sahih al-Bukhari Book 61, Hadith 118
← Previous Hadith While we were with Allah's Messenger (ﷺ) who was distributing (i.e. some property), there came Dhu-l- Khuwaisira, a man from the tribe of Bani Tamim and said, "O Allah's Messenger (ﷺ)! Do Justice." The Prophet said, "Woe to you! Who could do justice if I did not? I would be a desperate loser if I did not do justice." `Umar said, "O Allah's Messenger (ﷺ)! Allow me to chop his head off." The Prophet (ﷺ) said, "Leave him, for he has companions who pray and fast in such a way that you will consider your fasting negligible in comparison to theirs. They recite Quran but it does not go beyond their throats (i.e. they do not act on it) and they will desert Islam as an arrow goes through a victim's body, so that the hunter, on looking at the arrow's blade, would see nothing on it; he would look at its Risaf and see nothing: he would look at its Na,di and see nothing, and he would look at its Qudhadh ( 1 ) and see nothing (neither meat nor blood), for the arrow has been too fast even for the blood and excretions to smear. The sign by which they will be recognized is that among them there will be a black man, one of whose arms will resemble a woman's breast or a lump of meat moving loosely. Those people will appear when there will be differences amongst the people." I testify that I heard this narration from Allah's Messenger (ﷺ) and I testify that `Ali bin Abi Talib fought with such people, and I was in his company. He ordered that the man (described by the Prophet (ﷺ) ) should be looked for. The man was brought and I looked at him and noticed that he looked exactly as the Prophet (ﷺ) had described him.

Sahih al-Bukhari Book 61, Hadith 117 Next Hadith → We complained to Allah's Messenger (ﷺ) (of the persecution inflicted on us by the infidels) while he was sitting in the shade of the Ka`ba, leaning over his Burd (i.e. covering sheet). We said to him, "Would you seek help for us? Would you pray to Allah for us?" He said, "Among the nations before you a (believing) man would be put in a ditch that was dug for him, and a saw would be put over his head and he would be cut into two pieces; yet that (torture) would not make him give up his religion. His body would be combed with iron combs that would remove his flesh from the bones and nerves, yet that would not make him abandon his religion. By Allah, this religion (i.e. Islam) will prevail till a traveler from Sana (in Yemen) to Hadrarmaut will fear none but Allah, or a wolf as regards his sheep, but you (people) are hasty.

Sahih al-Bukhari Book 61, Hadith 119