Riyad as-Salihin (The Meadows of the Righteous)
by Imam Nawawi
232. Book of I'tikaf
1268. Ibn 'Umar said, "The Messenger of Allah, may Allah bless him and grant him peace, used to do i'tikaf for the last ten days of Ramadan." [Agreed upon]
1269. 'A'isha reported that the Prophet, may Allah bless him and grant him peace, used to do i'tikaf for the last ten days of Ramadan until Allah Almighty caused him to die. Then his wives did i'tikaf after him. [Agreed upon]
1270. Abu Hurayra said, "The Prophet, may Allah bless him and grant him peace, used to do i'tikaf for ten days every Ramadan. In the year in which he died he did i'tikaf for twenty days." [al-Bukhari]
