Bukhari

Hadith Commentary:
From all these narrations, Imam Bukhari rahimahullah intends to demonstrate that it is preferable to perform voluntary (nafl) prayers, even if they are offered during the day, in sets of two rak‘ahs.
This is also the position of Imam Shafi‘i rahimahullah.

Hadith Commentary:
(1)
From all these narrations, Imam Bukhari rahimahullah intends to establish that it is preferable to perform voluntary (nafl) prayers in sets of two rak‘ahs, even if they are offered during the daytime. The majority of the scholars of hadith have adopted this position. We have presented our detailed remarks regarding this under Hadith: 990. In this regard, Imam Bukhari rahimahullah has mentioned five ahadith:
The hadith of Abu Qatadah (444),
the hadith of Anas radi Allahu anhu (380),
the hadith of Abdullah ibn Umar radi Allahu anhu (937),
the hadith of Jabir ibn Abdullah radi Allahu anhu (930),
and the hadith of Abdullah ibn Umar radi Allahu anhu (397).
All these narrations have already been mentioned previously, and the related rulings have also been discussed.
Imam Bukhari rahimahullah has also mentioned two mu‘allaq (suspended) narrations:
The hadith narrated from Abu Hurairah radi Allahu anhu has been narrated by Imam Bukhari rahimahullah himself with a connected chain.
Similarly, the hadith of Utban ibn Malik radi Allahu anhu (425) has also been mentioned previously.

(2)
Hafiz Ibn Hajar rahimahullah has written that Imam Bukhari’s purpose is to refute those who say that voluntary prayers during the daytime should be performed in sets of four rak‘ahs. The position of the majority is that they should be performed by saying salam after every two rak‘ahs, whether they are offered during the day or at night. Imam Abu Hanifah and his two companions give the option in daytime prayers, but consider performing them in sets of four rak‘ahs to be preferable.
(Fath al-Bari: 3/65)