Tirmidhi

1:
The literal meaning of i'tikaf is to restrain and confine oneself.
In the legal (shar'i) terminology, i'tikaf refers to confining oneself in the mosque with a specific manner and condition.
I'tikaf is a Sunnah.
The Messenger of Allah (sallallahu alayhi wa sallam) always observed it regularly, and after him, the noble wives (azwaj mutahharat, radi Allahu anhunna) also continued to observe it regularly.

Hadith Commentary:
(1)
In the narration from Abdullah ibn Umar (radi Allahu anhu), there is an additional report that Abdullah ibn Umar (radi Allahu anhu) used to indicate to his student Nafi‘ the specific place in the Prophet’s Mosque where the Messenger of Allah (sallallahu alayhi wa sallam) used to observe i‘tikaf (spiritual retreat).
(Sahih Muslim, Kitab al-I‘tikaf, Hadith: 2781(1171))
And in the narration of Sunan Ibn Majah, it is mentioned that when the Messenger of Allah (sallallahu alayhi wa sallam) would observe i‘tikaf in the mosque, a bed or cot would be spread for him behind the “Pillar of Repentance.”
(Sunan Ibn Majah, Kitab al-Siyam, Hadith: 1774)

(2)
From these narrations, it is evident that the Messenger of Allah (sallallahu alayhi wa sallam) used to observe i‘tikaf in the mosque during the last ten days of Ramadan.
From the hadith of Aisha (radi Allahu anha), it is understood that this practice was not abrogated, as it continued until his passing.
Observing i‘tikaf is not exclusive to him, because the noble wives (azwaj mutahharat) also practiced it after the Messenger of Allah (sallallahu alayhi wa sallam).
There is no doubt that i‘tikaf is a confirmed Sunnah (sunnah mu’akkadah).
(Fath al-Bari: 4/346)
In any case, the ruling of i‘tikaf has not been abrogated.

(3)
Observing i‘tikaf in the mosque is equally applicable to both men and women.
Those who try to find a concession for women to observe i‘tikaf at home are incorrect.
Our position is that women should also observe i‘tikaf in the mosque, provided it is with the permission of the husband or guardian, and there is no fear of compromising modesty or privacy there.
Seclusion at home for the purpose of worship may be called spiritual retreat, but to call it i‘tikaf is questionable.

Hadith Commentary: Benefits and Issues:

➊ The literal meaning of i'tikaf is to stay, to remain, and to adhere. However, in the Shari'ah, for a person to remain in the mosque in a specific manner for worship is called i'tikaf, and it is, by consensus, a Sunnah. It takes place in the last ten days of Ramadan, and from a juristic perspective, even sitting in the mosque for some time with the intention of worship is also considered i'tikaf. Evidently, there is no established instance from you (the Prophet sallallahu alayhi wa sallam) of i'tikaf being less than ten days.

➋ According to Imam Malik rahimahullah, Imam Abu Hanifah rahimahullah, and the majority of scholars, fasting is a condition for i'tikaf. Clearly, if i'tikaf is in Ramadan, then fasting must be observed. However, according to Imam Shafi'i rahimahullah, fasting is not a condition for i'tikaf, because Ramadan itself is not a condition for i'tikaf. You (the Prophet sallallahu alayhi wa sallam) performed i'tikaf in Shawwal, and Umar radi Allahu anhu had made a vow for one day of i'tikaf.

➌ According to Imam Malik rahimahullah, Imam Shafi'i rahimahullah, Imam Ahmad rahimahullah, Imam Dawud rahimahullah, and the majority, the mosque is a condition for i'tikaf for both men and women. According to the Hanafis, a woman will perform i'tikaf in the mosque of her house. However, the wives of the Prophet (azwaj mutahharat radi Allahu anhunna ajma'in) used to perform i'tikaf only in the mosque; performing i'tikaf at home is not established from them. However, it is necessary that a woman should only perform i'tikaf in the mosque if proper arrangements for seclusion (purdah) are made, there is no fear of mixing between men and women, there is no risk to her chastity and modesty, and it is not based on any ill intention.

Benefits and Issues:
➊ The literal meaning of i'tikaf is: to bind oneself to something or to remain confined somewhere.
And in the legal (shar'i) terminology: for a person to confine himself in a mosque for the worship of the Lord of Majesty (Rabb Dhul-Jalal) is called i'tikaf.
Its being legislated, Sunnah, and recommended (mustahabb) is established from the practice of the Messenger of Allah (sallallahu alayhi wa sallam).
It is also mentioned in the Noble Qur'an: (And We commanded Ibrahim and Isma'il: "Purify My House for those who perform tawaf, and those who stay for i'tikaf, and those who bow and prostrate.") () We commanded Ibrahim and Isma'il (alayhimas-salam) to purify My House for those who perform tawaf, those who perform i'tikaf, and those who bow and prostrate.
In another verse, He said: (And do not approach your wives while you are in i'tikaf in the mosques.) () And as long as you are in i'tikaf in the mosques, do not have relations with women.
Some people think that among the people of a town, it is necessary for at least one person to perform i'tikaf; this is merely a misconception.
There is no legal basis for this.
Unless someone makes it obligatory upon himself, it is not obligatory.

➋ Women can also perform i'tikaf, provided that the husband gives permission.
And for a woman as well, the place of i'tikaf is the mosque, not the home.
However, it is necessary that there be adequate arrangements for privacy (purdah) and protection for women in the mosque.
In a mosque where such arrangements do not exist, it is not correct for women to perform i'tikaf there.
Similarly, performing i'tikaf in homes is also incorrect.

570 Benefit:
This is evidence that i'tikaf (spiritual retreat) is a Sunnah. The Prophet sallallahu alayhi wa sallam always observed it diligently, and after him, the noble wives (azwaj mutahharat) also continued to observe it diligently. [سبلا السلام] ٭