Bukhari

Explanation:
The meaning is that, generally, the lifespans of this Ummah will not exceed one hundred years, or that all the people alive on this night will be gone by the end of a hundred years. The negation of life here does not refer to the generations that will be born after this night. According to the scholars of verification (muhaqqiqin), this is the intended meaning, and this is what is apparent from the wording. Accordingly, the last Companion, Abu Tufayl ‘Amir ibn Wathilah, passed away exactly one hundred years later at the age of 110.

The meaning of «سمر» is to converse before sleeping at night. In the previous chapter, there was mention of giving admonition at night in general, and in this one, there is specific mention of scholarly discussions before sleeping. From this, the difference between the previous chapter and this one becomes clear. [فتح الباری]

The purpose is that teaching, learning, admonition, and reminder are permissible and correct at any time of day or night as needed. Especially for students, studying at night becomes imprinted on the heart and mind. From this hadith, Imam al-Bukhari rahimahullah has deduced evidence that the belief in the life of Khidr alayhis salam is not correct. If he were alive, he would certainly have met the Prophet sallallahu alayhi wa sallam. Some scholars do hold the view of his being alive. «والله اعلم بالصواب»

Hadith Commentary:
➊
The meaning of "samar" is the light of the moon; then, nighttime conversation came to be called "samar." This is because, in the era of ignorance, the Arabs would spend time in open fields after the rising of the moon, engaging in family boasts, storytelling, poetry, and frivolous talk. When the moon would set, they would return home. All these absurdities were also called "samar." In the Shariah, this is impermissible and forbidden. The purpose of Imam Bukhari rahimahullah is that if a portion of the night is spent in scholarly pursuits, it is not prohibited. In the previous chapter, scholarly issues were mentioned; now, scholarly debates and anecdotes are being discussed. Also, in the previous chapter, scholarly conversation after sleeping was established, and in this chapter, its proof is being given before sleeping after the 'Isha prayer. Imam Bukhari rahimahullah wants to clarify that there should not be "samar" after the 'Isha prayer; if it is done, it should be "samar" of knowledge and goodness, not the "samar" of the era of ignorance, because that is prohibited.

➋
In this hadith, the Messenger of Allah sallallahu alayhi wa sallam has warned us that, compared to the previous nations, your lifespans are very short, as is mentioned in the hadith: "The lifespans of my ummah are between sixty and seventy." (Jami' al-Tirmidhi, al-Zuhd, Hadith: 2331) Along with this difference in lifespan, there is also a great difference in responsibility. For them, the work was brief despite long lifespans, whereas for this ummah, the work is extensive despite short lifespans. On this basis, we should be fully engaged in fulfilling our duties, being mindful of our responsibilities. (Fath al-Bari: 1/280) From this hadith, it is also understood that Khidr is no longer alive, because according to this hadith, no one who witnessed the era of the Messenger of Allah sallallahu alayhi wa sallam remained alive after one hundred years. And Allah knows best.