Bukhari

Hadith Commentary:
From this, the position of Imam Shafi'i, Imam Ahmad, and the Ahl al-Hadith is established: that it is valid for someone performing an obligatory prayer to follow behind someone performing a supererogatory (nafl) prayer.
The Hanafis have, even here, resorted to far-fetched interpretations.
All of these are merely the result of sectarian bias, for example: regarding the displeasure of the Prophet (sallallahu alayhi wa sallam) with Mu'adh (radi Allahu anhu), it is written that perhaps he (the Prophet) became displeased because Mu'adh went and led the prayer again (see Tafheem al-Bukhari, vol. 3, p. 97).
This is such an interpretation that has no connection whatsoever to the actual incident.
"Qiyas kun z-gulistan man bahar mara" (Compare my spring to the rose garden).

Hadith Commentary:
(1)
If someone is troubled by the lengthy recitation of the imam, it is permissible for him to leave the imam’s following and pray alone, because according to the hadith, the Messenger of Allah (sallallahu alayhi wa sallam) did not reproach the one who stopped following the imam, but rather admonished the imam. However, Imam Bukhari (rahimahullah) wants to establish a jurisprudential issue from this hadith, which is: if a person is praying behind the imam and he leaves the following, should he continue the prayer from where he left off (bina) or should he repeat the entire prayer?

According to Imam Shafi’i (rahimahullah), he may continue (bina) from where he left off following the imam; there is no need to repeat the entire prayer. However, according to the majority, in this case, he cannot continue (bina), but must repeat the entire prayer.

Imam Bukhari (rahimahullah) inclines towards the view of the majority, as is evident from the narration in Sahih Muslim, that he ended the prayer by saying salam, then prayed alone in a corner.
(Sahih Muslim, al-Salat, Hadith: 1040 (465))

(2)
From Surah al-Hujurat to the end of the Qur’an, all the surahs are called “Mufassal.” Then, up to (عَمَّ يَتَسَاءَلُونَ ﴿١﴾) are known as the long (tawal) mufassal, up to (وَالضُّحَىٰ ﴿١﴾) as the medium (awsat), and up to (al-Nas) as the short (qisar) mufassal.

Generally, up to Surah al-Buruj are called the long (tawal), up to (لَمْ يَكُنِ الَّذِينَ كَفَرُوا) the medium (awsat), and up to (al-Nas) the short (qisar).

The narrator of the hadith, Hazrat Amr ibn Dinar, said that he forgot the two surahs which the Messenger of Allah (sallallahu alayhi wa sallam) recommended to be recited, but this was when he narrated the hadith to his student Hazrat Shu’bah. In contrast, when he narrated the hadith to Sulaiman ibn Hayyan, he clarified that the two surahs were (وَالشَّمْسِ وَضُحَاهَا ﴿١﴾) and (سَبِّحِ اسْمَ رَبِّكَ الْأَعْلَى ﴿١﴾).

In some narrations, along with these, (وَاللَّيْلِ إِذَا يَغْشَىٰ ﴿١﴾) and (اقْرَأْ بِاسْمِ رَبِّكَ الَّذِي خَلَقَ ﴿١﴾) are also mentioned.
(Fath al-Bari: 2/253)

(3)
From this hadith, it is understood that due to a legitimate Shar’i reason, a prayer can be performed twice in one day. However, it is not valid to perform a single obligatory prayer twice as an obligation.

Because there is a prohibition of this in the hadith, as the Messenger of Allah (sallallahu alayhi wa sallam) said:
“Do not perform a prayer twice in one day.”

Imam Bayhaqi (rahimahullah) has explained its practical application by stating that the first is considered obligatory (fard) and the second as supererogatory (nafl).

This practice is established from the Messenger of Allah (sallallahu alayhi wa sallam).
He said that if you have prayed at home and then get the opportunity to join the congregation, you should perform the same prayer again in congregation.

The second prayer will be considered nafl. Also, if a tyrannical ruler delays the prayer, then the same ruling applies: pray at home on time, then, to avoid discord, join their congregation and consider it nafl.
(Fath al-Bari: 2/255)

From this hadith, it is also understood that one may pray an obligatory prayer behind someone performing a supererogatory prayer, as is explicitly mentioned in some chains regarding Hazrat Mu’adh (radi Allahu anhu) that the prayer he performed the second time was nafl for him and obligatory for the people.
(Fath al-Bari: 2/254)