Thunderbolts will increase as the Hour approaches

It is narrated from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Near the Hour, lightning strikes will become so frequent that people will get up in the morning and ask one another: 'Whom did the lightning strike last night?' And the answer will be: 'Lightning struck so-and-so and so-and-so.'"
This hadith is sahih (authentic) on the condition of Muslim, but the two Shaykhs (Bukhari and Muslim) did not record it.

It is narrated from Sayyiduna Hudhayfah (may Allah be pleased with him) that he was asked: O Abu Abdullah! When those who pray (the Muslims) fight one another, what do you command us to do? He said: "I command you to seek out the furthest (innermost) corner of your house and crouch down there. Then if someone forces his way in to you, say to him (like the righteous son of Adam (peace be upon him)): 'Take upon yourself my sin and your sin.' Thus you will be like that (righteous) son of Adam."
This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but the two Shaykhs did not record it in their books.

Sayyiduna Abd al-Rahman bin Suhar al-Abdi narrates from his father that the Messenger of Allah (peace and blessings be upon him) said: "The Hour will not be established until tribes of the Arabs are swallowed up by the earth, so much so that people will ask (in astonishment): 'Who is left of Banu so-and-so?'" (The narrator says:) When he (peace and blessings be upon him) used the word "tribes", I understood that the Arabs were meant, because non-Arabs are attributed to their villages and towns.
This hadith has a sahih (authentic) chain, but the two Shaykhs (Bukhari and Muslim) did not record it.

It is narrated from Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "In my Ummah there will be the swallowing up by the earth, the transformation of forms, and the raining of stones (from the sky)."
If Abu al-Zubayr's hearing from Sayyiduna Abdullah bin Amr is established, then this hadith is sahih (authentic) on the condition of Muslim, but neither of them (Bukhari and Muslim) recorded it.

It is narrated from Sayyiduna Hudhayfah (may Allah be pleased with him) that he said: "It is as if I can see a rider who will come down among you and stand between the orphans and widows and the spoils (fay') that came to their forefathers (withholding it from them), and he will say: 'All this wealth is ours.'"
This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but neither of them recorded it in their books.