Bukhari

Hadith Commentary:
(1)
The main purpose of Imam Bukhari rahimahullah in citing this narration is to clarify the earliest time for the Dhuhr prayer, that the time for Dhuhr begins after the sun passes its zenith (zawal), and in fact, the Messenger of Allah sallallahu alayhi wa sallam would perform the Dhuhr prayer immediately after the sun had passed its zenith. In the mentioned narration, there is no distinction made between the seasons of winter and summer. From another narration, it is understood that during intense heat, the Dhuhr prayer would be delayed and performed when it became cooler, rather than at its earliest time. According to the narration, the narrator forgot regarding the Maghrib prayer as to what time it was performed; this is clarified by Jabir bin Abdullah radi Allahu anhu, who states that when the sun would set, the Maghrib prayer would be performed. (, , ) (Sahih al-Bukhari, Mawaqit al-Salat, Hadith: 560)

(2)
In the Fajr prayer, "isfar" means there was enough light that people could recognize one another. This would occur after the taslim (salutation ending the prayer). As is known from multiple narrations, in one narration it is stated that when we would finish the morning prayer with the taslim, we would look at acquaintances and recognize them by their faces. (Sahih Muslim, al-Masajid, Hadith 1462(647)) When, upon completing the prayer with the taslim, there was barely enough light to recognize only the companion sitting nearby, and you (sallallahu alayhi wa sallam) would recite between sixty and one hundred verses, then certainly the prayer would begin in "ghalas," that is, in deep darkness. And this is what is intended.

(3)
Imam Kirmani rahimahullah states: From this hadith, it is understood that the time for the Isha prayer is until one-third or half of the night, whereas from other ahadith it is understood that the Isha prayer can be performed until before the Fajr prayer. Thus, the Messenger of Allah sallallahu alayhi wa sallam said: "There is no negligence in sleep, but negligence is on the part of one who does not pray until the time for the next prayer has begun." There is no contradiction between these ahadith, because the mentioned hadith indicates the recommended and most virtuous time for Isha prayer, which is until one-third or half of the night. (Sharh al-Kirmani: 190/4)

(4)
Regarding the Isha prayer, it is clarified that there was no concern whether it was performed after one-third of the night or up to half the night. In reality, the congregation would be observed; if they gathered quickly for prayer, it would be performed early, and if for some reason they arrived late, the Isha prayer would be delayed up to half the night, as this noble practice of the Messenger of Allah sallallahu alayhi wa sallam has been transmitted in the ahadith. (Sahih al-Bukhari, Mawaqit al-Salat, Hadith: 565.) The clarification regarding the final time for the Isha prayer will follow.

Hadith Commentary: Benefits and Issues: The Messenger of Allah (sallallahu alayhi wa sallam) would sometimes recite up to one hundred verses in a single rak‘ah, and sometimes in both rak‘ahs, and on certain occasions, according to the situation and context, he (sallallahu alayhi wa sallam) recited less than this and sometimes more.

Hadith Commentary:
Benefits and Issues:
It is not permissible to sleep before the ‘Isha prayer in such a way that the congregational prayer is missed or its preferred time passes. However, if a person wakes up and is able to join the congregation, or due to some necessity has to perform it individually, then if he performs it within the preferred time, there is no harm in it. Similarly, if after ‘Isha one becomes engaged in some necessary religious or worldly conversation, and as a result, neither the tahajjud prayer nor at the very least the Fajr prayer is affected, then there is also no harm in this. But idle and purposeless conversation, or reading novels and stories, or watching television—activities due to which even the ‘Isha prayer is missed—are not correct.

949. Commentary: In the dawn (Fajr) prayer, reciting a longer portion of the Qur'an is Sunnah compared to the other prayers. Perhaps for this reason, its units (rak‘ahs) are fewer than those of all other prayers; however, the length of the recitation depends on the condition of the followers (muqtadis). The mention of sixty to one hundred words also conveys this same meaning.

Benefits and Issues:
(1)
This is a general estimation.
It does not mean that a lesser or greater amount is not permissible.
If the verses are long, then sixty verses may be recited.
For example, Surah As-Sajdah and Surah Al-Mulk both have thirty verses each.
So by reciting two surahs in two rak‘ahs, sixty verses will be completed.
And from surahs with short verses, one may recite one hundred verses, for example, Surah Al-Waqi‘ah can be divided and recited in both rak‘ahs,
which has ninety-six verses.
If the verses are very long, as in Surah Al-Baqarah and others, then the number may be even less than this.
Whatever amount of recitation can be done with ease, and the followers (muqtadis) can listen with ease, is permissible.