Bukhari

Hadith Commentary:
It is understood that the command of veiling (purdah) given to the noble wives (azwaj mutahharat) did not mean that they should not go outside the house at all; rather, the intent was that the parts of the body which are required to be concealed should be covered.
(Qastallani)

Hadith Commentary:
➊
Umar radi Allahu anhu was extremely protective; he disliked strangers obtaining information about the Mothers of the Believers radi Allahu anhunna ajma‘een.
He had a strong desire that they be kept in seclusion, to the extent that he explicitly said:
“O Messenger of Allah sallallahu alayhi wa sallam! Keep your wives in seclusion,” until the verses of hijab were revealed.
➋
This seclusion is called “hijab al-abdan” (concealment of the bodies), meaning that no part of the body is visible. However, even this level of seclusion did not satisfy Umar radi Allahu anhu; his wish was that the very personhood of the Mothers of the Believers radi Allahu anhunna ajma‘een be concealed as well.
This is referred to as “hijab al-ashkhas” (concealment of the persons).
That is why he said regarding Sawdah radi Allahu anha: “Sawdah radi Allahu anha! We have recognized you.” But this time, his wish was not fulfilled; rather, the command of Allah came that the Mothers of the Believers radi Allahu anhunna ajma‘een are permitted to go out, while observing hijab, to fulfill their needs, so that they are not put to hardship.
Allah knows best.

Hadith Commentary:

In today's critical era, the necessities of life and economic struggle have reached such an extent that, on many occasions, it becomes necessary for women as well to go outside the home. This is why Islam has not imposed any hardship in this matter; however, it is necessary that women go out while observing the Islamic limits of veiling (purdah).

Hadith Commentary:
(1)
For those matters for which it is permissible for women to go outside, such as visiting parents and meeting relatives and close kin, they are allowed to go out for such purposes. In addition, it is also permissible for them to go out for necessary needs.
(2)
In today’s delicate times, the necessities of life and the struggle for livelihood have reached such an extent that in most situations, it becomes necessary for women to go outside the home as well. In such circumstances, Islam has not imposed any hardship; however, it is necessary that they go out while observing the limits set by Shariah and maintaining proper covering (purdah).
And Allah knows best.

Explanation:
Even after the verse of hijab, it is established that sometimes women would go into the forest at night in the darkness. [فتح الباري]

Hadith Commentary:
➊
Among the Arabs, it was customary that they would go out to open fields for relieving themselves, to the extent that even the noble wives of the Prophet (radi Allahu anhunna) were accustomed to going outside for this purpose.
Among the Arabs, it was considered undesirable to arrange for relieving oneself inside the houses.
This chapter explains what should be done if the noble wives need to go outside for their needs. If they go during the day or leave without proper covering, it would be contrary to their dignity. Therefore, the method adopted was that the women would go to a separate field at night for relieving themselves, and they had so accustomed themselves to this that there was no need for it during the daytime.
Imam al-Bukhari rahimahullah has established the permissibility of this situation from this hadith.

➋
There is some apparent contradiction regarding the revelation of the verses about veiling (hijab).
From the mentioned hadith, it appears that the verse of hijab had not yet been revealed, whereas from another narration reported by Aisha (radi Allahu anha), it appears that the verse of hijab had already been revealed (Sahih al-Bukhari, Tafsir, Hadith: 4795).
Also, from this narration, it appears that with the revelation of the verse, the objective of Umar (radi Allahu anhu) was fulfilled, whereas from another narration, it appears that the intention of Ibn Umar (radi Allahu anhuma) was not fulfilled, and the Prophet (sallallahu alayhi wa sallam) said that you are permitted to go outside for relieving yourselves.
This is contrary to the intention of Umar (radi Allahu anhu).
Furthermore, from this narration, it appears that the incident of Sawdah (radi Allahu anha) became the cause for the revelation of the verse of hijab, whereas from another narration, it appears that the verse of hijab was revealed on the day of the wedding feast (walimah) of Zaynab bint Jahsh (radi Allahu anha), as is explicitly mentioned in Sahih al-Bukhari (Sahih al-Bukhari, Tafsir, Hadith: 4791).
In reality, there are two types of hijab:
Hijab of the Face (Hijab Wujuh):
(covering of the face)
When a woman comes before a non-mahram, she should cover her face.
Hijab of the Person (Hijab Ashkhas):
(covering of the entire person)
The woman’s person should not be seen at all, i.e., she should not go outside the house.
Umar (radi Allahu anhu) requested the Messenger of Allah (sallallahu alayhi wa sallam):
All kinds of people come to you; please command your noble wives (radi Allahu anhunna) to observe hijab. So the verse of hijab was revealed.
Thus, his wish was fulfilled.
(Sahih al-Bukhari, Tafsir, Hadith: 4790)
The verse of hijab is Surah al-Ahzab: 53, and it was revealed on the occasion of the wedding feast of Zaynab (radi Allahu anha), as mentioned earlier; this is the hijab of the face (hijab wujuh).
After this, Umar (radi Allahu anhu) had a second wish: that, just as the hijab of the face was commanded, the hijab of the person (not leaving the house) should also be commanded.
Umar’s (radi Allahu anhu) stopping Sawdah (radi Allahu anha) on the road was in this context, but in this matter, his wish was not fulfilled; rather, through revelation, it was informed that women are permitted to go outside for relieving themselves.
With this explanation, all apparent contradictions are resolved. However, after this, arrangements were made for relieving oneself inside the houses.
This does not mean that Umar (radi Allahu anhu) had more protective jealousy (ghayrah) than the Messenger of Allah (sallallahu alayhi wa sallam); rather, the Prophet (sallallahu alayhi wa sallam) had far greater protective jealousy than Umar (radi Allahu anhu), but he did not wish to act on any expediency without Allah’s revelation. Therefore, even though he felt the need, he did not issue any command regarding hijab until revelation came.
(Fath al-Bari: 1/327, 328)

Benefits:

➊ This hadith mentions the virtue of Umar ibn al-Khattab radi Allahu anhu, and that it is permissible to admonish and repeatedly remind people of virtue and prominent personalities for their own interests and well-wishing.

➋ This indicates the permissibility of sucking on a bone.

➌ It is permissible for a woman to go to designated places for relieving herself without her husband's permission, because the Shari‘ah has granted her this allowance.

[نووي: 150/14]

➍ Ibn Battal rahimahullah says: This hadith is evidence that women may go out to visit their parents and relatives, and likewise, it is permissible for them to leave the house for necessary needs. This is similar to the ruling regarding going out to the mosque.

Mahlab rahimahullah says: It is permissible to speak to a non-mahram woman from behind a veil (screen).

[شرح ابن بطال: 367/13]