I'tikaaf [The Spiritual Retreat] and its Types

Hadrat Sayyidah 'Ayeshah Siddiqah Radi ALLAHu Ta'ala Anha reported that the Holy Prophet Peace and Blessings be Upon Him used to engage in I'tikaaf. i.e. private devotions in the mosque during the last ten nights of Ramadan till he met his Lord. [Sahih Bukhari, Vol 1, Page 271 - Sahih Muslim, Vol 1, Page 371] Hadrat Anas Radi ALLAHu Ta'ala Anhu reported that the Holy Prophet Peace and Blessings be Upon Him used to engage in I'tikaaf in the mosque in the last ten days of Ramadan. But, one year he omitted the I'tikaaf so he engaged in I'tikaf during twenty nights the following year. [Sunan Abi Dawood, Vol 1, Page 334]

Important Notes:

1. It is sunnat-e-Mu'akkadah to perform I'itikaf in the mosque in the last ten days of the month of Ramadan, as stated by Hadrat Sheikh 'Abd al-Haq "Muhaddith-e-Dehlwi": According to the Hanafi madhhab, I'itikaf is Sunnat-e-Mu'akkadah as the Holy Prophet always used to perform it till he passed away. [Ashi'ah al-Lam'at Vol. 2 Pg. 118]
2. There are 3 types of I'itikaf:
a) Wajib – if one makes a "Minnat" (vow) of I'itikaf uttering the words of vow. Mere intention will not make I'itikaf wajib. For example, one says, "If my child becomes cured from his illness then I shall perform I'itikaf for three days." Then to perform I'itikaf for three days with fast is wajib.
b) Sunnat-e-Mu'akkadah – that one should enter the Masjid on the 20th of Ramadhan before sunset, with the intention of I'itikaf and to stay there till the end of Ramadhan i.e. leave the mosque after the Maghrib prayer on the 30th of Ramadan or if the moon for Eid was sighted on the 29th then to leave after the Maghrib prayer of that day. This I'itikaf is "sunnat-e-Kifayah" meaning that if I'itikaf was performed by even one person in a town then the religious duty shal be fulfilled on behalf of everyone. Otherwise, all shall be accountable for neglecting it.
There are many virtues and excellences for such an I'itikaf. Baihaqi has reported on the authority of Hadrat Imam Husain that the Messenger of Allah has stated, "whosoever performs I'itikaf for ten days in the month of Ramadan, it is as though he has performed two 'Umrah (lesser pilgrimage) and two Hajj (greater pilgrimage)."
c) MustaHab or Sunnat-e-Mu'akkadah – I'itikaf other than the two types mentioned above are "Mustahab" and "Sunnat-e-Ghair Mu'akkadah" [Fatawa-e-'Alamgiri, Vol 1, Page 197]

  3. The mu'takif (person performing the I'itikaf) should not engage himself in worldly talks (as this is strictly forbidden in the Masjid, and in the state of I'itikaf it is even more so). Rather, the mu'takif should engage himself in the recitation of the Holy Qur'an; reading the Ahadith (Sayings) of the Holy Prophet; sending Durud sharif (salutations) upon the Beloved Prophet in abundance; learning and teaching Islamic knowledge; reading the life of our Noble Prophet as well as the other Prophets, Saints; writing Islamic books; listening to Islamic lectures and being engaged in the dhikr (remembrance) of Allah, the Most Exalted. [This has been stated in Fatawa-e-'Alamgiri, Vol 1 Page 198]
4. The easy method of performing a Mustahab I'itikaf is to make the intention of I'itikaf, (with the intention of entry to the masjid,) when one enters into the Masjid. For as long as he shall remain in the Masjid, he shall also earn the reward of being in I'itikaf. The words for the intention of the I'itikaf are:
بسم الله دخلت و عليه توكلت و نويت سنت الاعتكاف۔ اللهم افتح لي ابواب رحمتكك
"With the Blessed Name of Allah have I entered (into the Masjid) and in Him have I placed my trust, and I have made the intention of the Sunnah of I'itikaf. O Allah open Your doors of Mercy upon me."

— — —
Extracted From
Anwaar al-Hadith, Chapter 6, Pages 163 to 165
by Hadrat Allama Mufti Jalal al-Din Qadiri al-Amjadi
English Translation: Mawlana Kalim al-Qadiri [Bolton – U.K.]