عن أبي هريرة رضي الله عنه قال : كان النبي صلى الله عليه و سلم يعتكف في كل رمضان عشرة أيام فلما كان العام الذي قبض اعتكف عشرين يوما . رواه البخاري
Abu Hurairah (May Allah be pleased with him) reported: The Prophet (PBUH) used to observe I`tikaf every year (during Ramadan) for ten days; in the year in which he passed away, he observed I`tikaf for twenty days.
[Al-Bukhari].
Commentary: We learn from these Ahadith that the observance of I`tikaf in the last ten days of Ramadan is Sunnah of the Prophet (PBUH). But it can be done only in mosque not at home. I`tikaf helps to enhance one's spiritual growth and to strive hard to worship Allah better as there is nothing to distract one's attention from this noble pursuit