Concerning I`tikaaf...

Its Prescription:

1. Itikaaf (secluding oneself in the masjid) is a recommended act in Ramadaan as well as any other day in the year.  The source for that is found in Allah's saying: …while you are making Itikaaf in the masaajid.  And there are also many authentic Ahadeeth concerning the Prophets (saws) Itikaaf and narrations from the Salaf concerning that also. They are mentioned in the Musnnafs of Ibn Abi Shaibah and Abdur-Razzaaq.

It is authentically established that the Prophet (saws) made Itikaaf in the last ten days of Shawaal [This is a portion of a hadeeth from Aaishah reported by Al-Bukhari, Muslim and Ibn Khuzaimah in their Saheeh collections. I have referenced it in Saheeh Sunan Abi Dawood (2127)], and that Umar said to the Prophet (saws): I made an oath (to Allah) in the Days of Ignorance that I would make Itikaaf for one night in the Masjid Al-Haraam?  So the Prophet (saws) said: Fulfill your oath.  So he made Itikaaf one night. [Al-Bukhari, Muslim and Ibn Khuzaimah.  The extra addition is from Al-Bukhari in one narration as is stated in my abridgment to it (995)]

2. Observing it in Ramadaan is established in the hadeeth of Abu Hurairah: Allah's Messenger (saws) would make Itikaaf for ten days in every Ramadaan.  But when it was the year in which he died, he made Itikaaf for twenty days. [Al-Bukhari and Ibn Khuzaimah in their Saheeh collections and it is referenced in the previously mentioned source (2126-2130)]

3. The best time to do it is in the last part of Ramadaan because the Prophet (saws) would make Itikaaf during the last ten days of Ramadaan until Allah took his soul (in death). [Al-Bukhari and Muslim and Ibn Khuzaimah (2223) and it is referenced in Al-Irwaa (966) and Saheeh Abi Dawood (2125)]

Its Conditions:

1. Its observance is not legislated except in the masaajid, based on Allah's saying: And do not have intercourse with them (your wives) while you are making Itikaaf in the masaajid. [Surat-ul-Baqarah: 187. Imaam Al-Bukhari used this ayah as evidence for hat we have stated above. Al-Haafidh Ibn Hajr said: The point of evidence found in this ayah is that if it were correct to do Itikaaf in someplace other than a masjid, the forbiddance of having sexual relations would not be specifically mentioned, because sexual intercourse is forbidden during Itikaaf according to the consensus of the scholars. So it is understood through the mentioning of masaajid that the meaning is that Itikaaf is not correct except in it the masaajid.]

And Aaishah said: The Sunnah for the one doing Itikaaf is that he should not go out (of the masjid) except for some need that he must fulfill.  He should not witness a funeral, nor should he touch his wife, or have intercourse with her.  And there is no Itikaaf except in a masjid that establishes the Jamaaah (congregational prayer).  And the Sunnah for the one doing Itikaaf is that he should be fasting (on the day he makes Itikaaf). [Al-Baihaqi with an authentic chain, and Abu Dawood with a sound chain]

2. The masjid should also hold the Jumuah prayers so that he is not forced to leave the masjid to pray the Jumuah prayer. This is because going out for it is an obligation, based on Aaishah's saying in one report from her of the previous hadeeth: …and there is no Itikaaf except in a masjid that holds the Jumuah prayer. [Al-Baihaqi reported on Ibn Abbaas that he said: Verily, the most hated of things to Allaah are the innovations.  And verily from the innovations is making Itikaaf in the masaajid that are located in the houses."]

Furthermore, I came upon an authentic hadeeth that clearly specifies the masaajid mentioned in the previous ayah to mean the three masaajid: Masjid Al-Haraam, Masjid An-Nabawee and Masjid Al-Aqsaa. The hadeeth is: There is no Itikaaf except in the three masaajid. [At-Tahawi and Al-Ismaeli and Al-Baihaqi with an authentic chain of narration]

According to what I came across, those among the Salaf who held this opinion were Hudhaifah Ibn Al-Yamaan, Saeed Ibn Al-Musayyib and Ataa. However, he (Ataa) did not mention Masjid Al-Aqsaa. Others held the opinion that it was any congregating masjid (in which the Jumuah prayer is held), without restriction. And yet others disagreed saying it can even be done in the masjid of ones home. And there is no doubt that adhering to what complies with the hadeeth about it is what deserves to be followed. And Allah, Glorified and Exalted, knows best.

3. It is from the Sunnah for the one making Itikaaf to observe fasting, as has been stated by Aaishah. [Al-Baihaqi with an authentic chain of narration and Abu Dawood with a sound chain of narration]

What is permissible for the person making Itikaaf:

1.  It is permissible for him to leave the masjid in order to fulfill a need. And it is permissible for him to stick his head out of the masjid to have it washed and combed. Aaishah said: And the Messenger of Allah (saws) would enter his head in my presence while he was making Itikaaf in the masjid, and I was in my apartment.  So I would comb his hair, [and in one narration: I would wash it, even though there was the threshold between me and him, and I would be menstruating].  And he (saws) would not enter the house unless he had a [human] need, while making Itikaaf. [Al-Bukhari, Muslim, Ibn Abi Shaibah, and Ahmad, and the first addition belongs to these last two (mentioned)]

2. It is permissible for the one making Itikaaf and others to make wudoo (ablution) in the masjid, based on the saying of a man who would serve the Prophet (saws): The Prophet (saws) would make a light wudoo (ablution) in the masjid. [Al-Baihaqi with a good chain and Ahmad (5/364) in abridged form with an authentic chain]

3. He may set up a small tent in the back of the masjid in which to make Itikaaf. This is since Aaishah would set up a khibaa (tent - A khibaa is one type of house of the Arabs made form fur or wool, and it is not from hair. And it is set up on two or three props) for the Prophet (saws) when he would make Itikaaf. And this was from his (saws) command. [Al-Bukhari and Muslim]

And one time he made Itikaaf in a small tent that had a mat covering its doorway. [It is part of a hadeeth narrated by Abu Saeed Al-Khudri, reported by Muslim and Ibn Khuzaimah in their Saheehs] 

The Allowance of a woman to make ‘Itikaaf and visit her husband (who is making ‘Itikaaf) in the masjid:

4. It is permissible for a woman to visit her husband while he is making ‘Itikaaf. And he may walk with her to bid her farewell up to the door of the masjid, based on the saying of Safiyyah:

“The Prophet (saws) was making ‘Itikaaf in the masjid during the last ten days of Ramadaan, so I went to visit him one night, and his wives were with him.  So I spoke to him for an hour, then I got up to leave and he said: ‘Don’t rush, I’ll go out with you.’  So he got up with me to escort me out.”  And her dwelling used to be in the home of Usaamah Ibn Zaid.  Then they walked until they reached the door of the masjid, which was by the door of Umm Salamah.  Then two men from the Ansaar passed by and when they saw the Prophet (saws), they rushed away.  So the Prophet (saws) said: ‘Slow down!  This is (my wife) Safiyyah Bint Huyai’ So they said: ‘SubhanAllah, O Messenger of Allah.’  He (saws) said: ‘Verily, the Devil flows through the human like the flowing of blood.  And I feared lest he put some evil into your hearts.’”  [Or he (saws) said: “something into your hearts.”] [Al-Bukhari and Muslim and also Abu Dawood, and the last part of it is form him (Abu Dawood)]

Rather it is even permissible for a woman to make ‘Itikaaf along with her husband in the masjid or by herself, based on the statement of ‘Aa’ishah: ”One of the wives of Allah’'s Messenger (saws) made ‘Itikaaf with him while she was in the state of Istihaada (bleeding between periods) [in another narration it states she is Umm Salamah] and she would see red (blood) or yellowish traces (come out of her).  And sometimes we put a tray beneath her when she offered the prayer.” [Al-Bukhari and it is referenced in Saheeh Sunan Abi Dawood (2138). The other narration is from Sa’eed Ibn Mansoor, as is I stated in Fath-ul-Baari (4/281). However, Ad-Daarimi (1/22) says that she is Zainab, and Allah knows best.]

And she also said: “The Prophet (saws) would observe ‘Itikaaf during the last ten days of Ramadaan, until he died.  Then his wives observed ‘Itikaaf after him.” [Al-Bukhari, Muslim and others.]

There is proof in this that it is permissible for the women to make ‘Itikaaf also. And there is no doubt that this is on the condition that their guardians grant them permission to do that. And it is also on the condition that the place is free from any fitnah and intermingling with men, based on the many evidences for that and also on the Fiqh principle: “Preventing an evil takes precedence over bringing about a good.”

5. Having sexual intercourse nullifies one’s ‘Itikaaf, based on Allah'’s saying: “And do not have sexual relations with them (your wives) while you are making ‘Itikaaf in the masaajid.”

And Ibn ‘Abbaas said: “If the person making ‘Itikaaf has sexual relations then he nullifies his ‘Itikaaf and must start it over again.” [Ibn Abi Shaibah (3/92) and ‘Abdur-Razaaq (4/363) with an authentic chain of narration. and what is meant by his saying: “must start it over” is that he must redo his ‘Itikaaf]

There is no recompense (kaffaarah) that is binding upon him due to a lack of anything being mentioned about that by the Prophet (saws) and his Companions.

[Source: Qiyaam Ramadaan (pg. 34-41) - By Shaykh Muhammad Nasiruddin al-Albani]