(1) باب الاِعْتِكَافِ فِي الْعَشْرِ الأَوَاخِرِ وَالاِعْتِكَافِ فِي الْمَسَاجِدِ كُلِّهَا
Narrated `Aisha:
(the wife of the Prophet) The Prophet (ﷺ) used to practice I`tikaf in the last ten days of Ramadan till he died and then his wives used to practice I`tikaf after him.
Reference: Sahih al-Bukhari 2026
In-book reference: Book 33, Hadith 2
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 3, Book 33, Hadith 243