Imam al-Bukhārī transmits in his Ṣaḥīh from ˁĀˀishah, the mother of the believers, may Allah be pleased with her, “the Messenger of Allah, may peace and blessings be upon him, used to do iˁtikāf in the last ten days of Ramadan until Allah, the invincible and the majestic, completed his term. Then his wives performed iˁtikāf after him.” Imam al-Bukhārī also transmits from Abū Hurayrah, may Allah be pleased with him, “the Prophet, may blessings and peace be upon him, used to do iˁtikāf in every Ramadan for ten days, and when it was the year in which his life was taken, he did iˁtikāf for twenty days.”
Iˁtikāf is remaining in the mosque while fasting with the intention to please Allah. It is of three types: obligatory which is an iˁtikāf one pledges to Allah as an act of worship; Sunnah, which is in the last ten days of Ramadan; and recommended, which is any iˁtikāf other than the previous two. As the two hadiths show, performing iˁtikāf in the last ten days of Ramadan is an emphasized Sunnah that the Prophet, may peace and blessings be upon him, persisted upon until he passed away. Men perform iˁtikāf in a masjid in which the five daily ṣalāt are performed in congregation, while women perform it in their houses in a room which they designate for this purpose. During iˁtikāf, the Muslim waits to perform the farḍ (obligatory) ṣalāt and does not leave the place of iˁtikāf except to use the restroom, eating and sleeping in the place of iˁtikāf, devoting himself to the worship of Allah, through salāt, dhikr (remembrance of Allah), and recitation of the Noble Qurˀān. Marital intimacy is prohibited during iˁtikāf. Since Laylat al-Qadr (the night of power), is most likely in the last ten days of Ramadan, iˁtikāf also gives the opportunity to spend this blessed night in worship.
Working Muslims in the modern world might not be able to take the last ten days off from work, but we should remember the maxim that what is not attained totally should not be abandoned totally. If one cannot do the Sunnah iˁtīkāf of ten days, one can still do the recommended iˁtikāf for fewer days, even if it is just one or more. All praise belongs to Allah for showing us how to worship Him in such a way that pleases Him.