Nasai

Hadith Commentary:
1.
Some commentators have written that the hadith of Maymunah (radi Allahu anha) has no relevance to the chapter heading, because in this hadith the quantity of the vessel is not mentioned, whereas the chapter heading mentions its quantity.
Hafiz Ibn Hajar (rahimahullah) has answered this by saying that the relevance will be established by adding another premise, which is that the vessels of those people were small.
As Imam Shafi’i (rahimahullah) has clarified at several places.
Therefore, this hadith falls under the category of “similar to it.”
The second answer given is that the unrestricted word (ina’) (vessel) mentioned in the hadith of Maymunah (radi Allahu anha) will be interpreted in light of the restricted word (farq) in the hadith of Aisha (radi Allahu anha), because both were wives of the Messenger of Allah (sallallahu alayhi wa sallam) and each performed ritual bath (ghusl) with him, so each would have used more than one sa’ of water. Therefore, the vessel mentioned in the hadith of Maymunah will, approximately, fall under the subject of the chapter.
(Fath al-Bari: 1/476)
2.
Imam Bukhari (rahimahullah) has given preference to the narration of Ibn Abbas (radi Allahu anhuma) as transmitted by Abu Nu’aym over the narrations of others, meaning he has considered his own narration to be from the Musnad of Ibn Abbas (radi Allahu anhuma), while others consider it from the Musnad of Maymunah.
The reason he has stated is that attributing it to the Musnad of Maymunah relates to the later years of Ibn ‘Uyaynah (rahimahullah), whereas the Musnad of Ibn Abbas pertains to his earlier years, in which his memory was stronger. However, Hafiz Ibn Hajar (rahimahullah) has also considered the narration of the others to be preferable.
The reasons for this are as follows:
* In his later years, those who narrated from him were greater in number and had the opportunity to remain with their shaykh for a longer period.
* Ibn Abbas (radi Allahu anhuma) himself could not have been aware of the manner in which the Messenger of Allah (sallallahu alayhi wa sallam) performed ritual bath (ghusl) with Maymunah (radi Allahu anha), so he must have learned of it from Maymunah (radi Allahu anha) herself.
(Fath al-Bari: 1/476)
A third reason has been mentioned by ‘Allamah ‘Ayni, that Muslim, Nasa’i, Tirmidhi, and Ibn Majah—all four—have narrated this hadith from Ibn Abbas (radi Allahu anhuma) from Maymunah, meaning that according to these hadith scholars, this narration is from the Musnad of Maymunah.
(‘Umdat al-Qari: 3/17)
In Musnad Humaydi as well, this narration is reported from Maymunah (radi Allahu anha).
(Musnad al-Humaydi, no. 309)

1:
And if ritual bath (ghusl) is permissible, then ablution (wudu) is permissible all the more so.