Bukhari

Hadith Commentary:
In this narration, Abu Hurairah (radi Allahu anhu) has explained the reason why he narrated more hadiths compared to many other companions.
What he means is that he made more effort than others to remember the sayings and actions of the Prophet (sallallahu alayhi wa sallam).
In another narration, he also said that he was always with the Messenger of Allah (sallallahu alayhi wa sallam), he had no family or dependents, he had no concern for earning food, he spent his days in the Prophet’s Mosque with the poor companions who lived in the Suffah, and he never left the company of the Prophet (sallallahu alayhi wa sallam).
That is why he heard more hadiths from the Prophet (sallallahu alayhi wa sallam) than others, and since he preserved them as well, he narrated them.
This hadith has already appeared earlier in the Book of Knowledge (Kitab al-‘Ilm).
The opportunity for its discussion was also there.
Imam Bukhari (rahimahullah) has collected these hadiths under a specific chapter heading because he wants to show that if, while performing prayer, a thought comes to mind or something is pondered upon, the prayer is not invalidated.
Thoughts and worries are such things that it is not possible to avoid them completely.
However, even here, the nature and type of thoughts must be taken into consideration.
If thoughts related to matters of the Hereafter come during prayer, they will have less effect on the virtues of the prayer compared to worldly matters.
(Tafheem al-Bukhari)
The correspondence between the chapter and the hadith is that the companion would be absorbed in prayer and in thoughts.
Even so, he was not commanded to repeat the prayer.

Hadith Commentary:
(1)
The relevance of this hadith to the chapter heading is as follows: that person remained occupied with worldly thoughts during the prayer, and as a result, he was unable to retain the recitation of the Messenger of Allah (sallallahu alayhi wa sallam). Doing so does decrease the level of humility and submissiveness (khushu‘ and khudu‘), but it does not invalidate the prayer. In contrast, Abu Hurairah (radi Allahu anhu) reflected on the recitation of the Messenger of Allah (sallallahu alayhi wa sallam) during the prayer, and thus he remembered those surahs which the Messenger of Allah (sallallahu alayhi wa sallam) had recited in the prayer the previous night. (Fath al-Bari: 3/119) In any case, the occurrence of thoughts during prayer does not cause any defect in the prayer.

(2)
It is also understood from this that Abu Hurairah (radi Allahu anhu) had greater retention and precision than others.

(3)
The objection against Abu Hurairah (radi Allahu anhu) was raised after the life of the Messenger of Allah (sallallahu alayhi wa sallam). He responded to this objection by reasoning from an incident that occurred during the time of the Messenger of Allah (sallallahu alayhi wa sallam), that is, I used to be concerned with the sayings and actions of the Messenger of Allah (sallallahu alayhi wa sallam), and I would reflect upon them, while the rest of the people were occupied with their farming and business.

(4)
In any case, Imam Bukhari (rahimahullah) wants to clarify that if a thought occurs or some reflection takes place while performing the prayer, the prayer is not invalidated, because thoughts and reflections are such things that cannot be controlled. However, the nature of the thoughts must certainly be taken into consideration. If, during the prayer, thoughts related to matters of the Hereafter occur, then they will have less effect on the virtues of the prayer compared to worldly matters. And Allah knows best.